Grade 7Reading: grades 7-9MultiplicationIntegersPercentagesOrder of operationsTwo-step equations
The Lost Idol of El Dorado
A rival explorer has swiped the Golden Jaguar Idol right out of the excavation camp! The lead cartographer was tied up with vines, leaving only a trail of muddy boot prints and dropped gear. We must analyze the evidence left behind to figure out which member of the expedition turned rogue.
Suspects
Possible suspects
Cross off a row as each clue rules it out. On screen, tap a row.
21 of 21 still in play
| Name | Exploration Specialty | Backpack Tool | Handedness | Headgear worn | Phobia |
|---|---|---|---|---|---|
| Finn | decoding lens | sample vials | right handed compass use | canvas pith helmet | scared of fruit bats |
| Leo | climbing ropes | field journal | left handed compass use | canvas pith helmet | allergic to pollen |
| Jacques | decoding lens | field journal | right handed compass use | bright red bandana | allergic to pollen |
| Sacagawea | machete tool | pocket flares | left handed compass use | canvas pith helmet | afraid of heights |
| Mateo | decoding lens | smoke bombs | right handed compass use | canvas pith helmet | afraid of heights |
| Hudson | climbing ropes | smoke bombs | right handed compass use | canvas pith helmet | scared of fruit bats |
| Gemma | metal detector | pocket flares | left handed compass use | canvas pith helmet | afraid of heights |
| Indy | decoding lens | sample vials | right handed compass use | bright red bandana | allergic to pollen |
| Lara | grappling hook | field journal | right handed compass use | brown leather cap | afraid of heights |
| Percy | machete tool | tracking radar | left handed compass use | canvas pith helmet | afraid of heights |
| Freya | metal detector | pocket flares | left handed compass use | brown leather cap | afraid of heights |
| Isabella | grappling hook | tracking radar | left handed compass use | bright red bandana | afraid of heights |
| Marco | machete tool | pocket flares | right handed compass use | bright red bandana | allergic to pollen |
| Elena | decoding lens | sample vials | left handed compass use | brown leather cap | allergic to pollen |
| Nellie | machete tool | sample vials | right handed compass use | brown leather cap | scared of fruit bats |
| Amelia | climbing ropes | sample vials | left handed compass use | brown leather cap | afraid of heights |
| Zelda | metal detector | field journal | left handed compass use | canvas pith helmet | allergic to pollen |
| Wyatt | machete tool | sample vials | left handed compass use | canvas pith helmet | afraid of heights |
| Charles | machete tool | sample vials | right handed compass use | bright red bandana | scared of fruit bats |
| Arthur | machete tool | smoke bombs | left handed compass use | canvas pith helmet | afraid of heights |
| Cora | decoding lens | sample vials | right handed compass use | canvas pith helmet | afraid of heights |
Clue 1
Multiplication facts (1-12)
To calculate the grid coordinates of the lost temple's entrance, we need to multiply the number of columns in the ancient relief carvings.
Solve each problem to learn its letter. Then write that letter in every box that shows the same number, and read the secret clue.
T
32
77
42
T
32
20
22
28
42
T
32
2
4
42
27
72
4
T
32
35
27
42
27
55
4
6
42
3
4
55
3
27
4 × 8 =T
6 × 7 =E
10 × 2 =A
9 × 3 =S
1 × 6 =K
7 × 4 =G
3 × 1 =B
5 × 7 =U
12 × 6 =N
1 × 2 =D
2 × 11 =R
5 × 11 =M
11 × 7 =H
2 × 2 =O
0/14 letters found
Clue 2
Integers
The altitude dial in our steam-powered balloon fluctuated wildly, dropping below sea level before rising again as we charted the temperature shifts.
Solve each problem to learn its letter. Then write that letter in every box that shows the same number, and read the secret clue.
T
24
9
11
18
14
20
25
21
26
T
24
9
11
20
27
T
24
9
11
18
10
1
25
6
22
22
26
12
T
24
9
11
20
11
28
T
24
9
6
12
27
20 - (-4) =T
(-11) + 23 =N
(-11) + 25 =U
18 - (-4) =S
14 - (-14) =F
6 - (-12) =C
(-10) + 37 =D
(-12) + 23 =E
(-12) + 18 =A
21 - (-4) =P
(-4) + 13 =H
10 - (-11) =R
17 - (-9) =I
1 - (-9) =O
8 - (-12) =L
(-13) + 14 =M
0/16 letters found
Clue 3
Percentages
We analyzed the composition of the mysterious golden idol, calculating what portion of the alloy was pure copper versus ancient brass.
Solve each problem to learn its letter. Then write that letter in every box that shows the same number, and read the secret clue.
T
7
44
51
30
38
19
19
28
38
18
49
44
38
30
51
5
51
9
34
44
38
19
51
28
T
7
T
7
44
51
44
38
32
44
41
19
38
52
52
20% of 35 =T
50% of 98 =S
10% of 280 =A
25% of 204 =E
25% of 76 =L
50% of 76 =I
5% of 640 =G
25% of 176 =H
50% of 36 =N
40% of 130 =F
50% of 60 =V
50% of 18 =D
50% of 68 =W
20% of 25 =R
50% of 82 =C
0/15 letters found
Clue 4
Order of operations
Before we could disarm the pressure-plate trap in the treasure room, we had to solve the nested equation carved into the stone lintel.
Solve each problem to learn its letter. Then write that letter in every box that shows the same number, and read the secret clue.
A
45
92
A
45
118
79
A
45
43
110
78
117
27
27
22
85
99
22
117
81
A
45
43
85
22
109
117
78
118
117
27
22
99
11
9
12 × 4 - 3 =A
86 + 3 × 2 =C
11 × 12 - 22 =P
10 + 2 × 6 =E
72 + 3 × 3 =W
55 + 7 × 9 =N
12 + 5 × 3 =H
8 + 5 × 7 =S
7 + 2 × 2 =U
12 × 11 - 23 =F
3 + 3 × 2 =D
93 + 6 × 4 =T
10 × 9 - 11 =V
11 × 11 - 22 =M
48 + 5 × 6 =I
10 × 9 - 5 =L
0/16 letters found
Clue 5
Two-step equations — the last clue
We need to balance the fuel consumption rate of our expedition buggy to see how many miles remain before we run out of water.
First solve each problem. Then find each answer in the list below and cross that sentence out. One sentence will be left — that's exactly what the villain did!
Step 1 — solve these
2x + 8 = 10, x = ?
3x + 8 = 23, x = ?
4x + 3 = 35, x = ?
5x + 11 = 56, x = ?
3x + 1 = 7, x = ?
6x + 3 = 69, x = ?
3x + 7 = 43, x = ?
2x + 1 = 21, x = ?
5x + 8 = 23, x = ?
3x + 8 = 26, x = ?
4x + 10 = 26, x = ?
Step 2 — cross out the sentence with each answer
1.The villain cleared the dense vines with a machete tool, then lit up the dark cavern using pocket flares.
2.The villain swung across the canyon with a grappling hook, then scooped up glowing mud into sample vials.
3.The villain read the hidden runes with a decoding lens, then escaped in a cloud of thick smoke bombs.
4.The villain scaled the ancient ruins with climbing ropes, then scooped up glowing mud into sample vials.
5.The villain scanned the dirt path with a metal detector, then lit up the dark cavern using pocket flares.
6.The villain scaled the ancient ruins with climbing ropes, then lit up the dark cavern using pocket flares.
7.The villain cleared the dense vines with a machete tool, then scooped up glowing mud into sample vials.
8.The villain cleared the dense vines with a machete tool, then tracked the native wildlife with radar.
9.The villain swung across the canyon with a grappling hook, then lit up the dark cavern using pocket flares.
10.The villain cleared the dense vines with a machete tool, then escaped in a cloud of thick smoke bombs.
11.The villain cleared the dense vines with a machete tool, then sketched a secret route in a field journal.
12.The villain read the hidden runes with a decoding lens, then scooped up glowing mud into sample vials.
Solve it
Name the culprit
Choose the one suspect left standing.
Answer Key — The Lost Idol of El Dorado
Culprit: Wyatt (machete tool · sample vials · left handed compass use · canvas pith helmet · afraid of heights)
- Clue 1 (Multiplication facts (1-12)): "THE TARGET DOES NOT USE SMOKE BOMBS"4 × 8 = 32 (T) · 6 × 7 = 42 (E) · 10 × 2 = 20 (A) · 9 × 3 = 27 (S) · 1 × 6 = 6 (K) · 7 × 4 = 28 (G) · 3 × 1 = 3 (B) · 5 × 7 = 35 (U) · 12 × 6 = 72 (N) · 1 × 2 = 2 (D) · 2 × 11 = 22 (R) · 5 × 11 = 55 (M) · 11 × 7 = 77 (H) · 2 × 2 = 4 (O)
- Clue 2 (Integers): "THE CULPRIT HELD THE COMPASS IN THE LEFT HAND"20 - (-4) = 24 (T) · (-11) + 23 = 12 (N) · (-11) + 25 = 14 (U) · 18 - (-4) = 22 (S) · 14 - (-14) = 28 (F) · 6 - (-12) = 18 (C) · (-10) + 37 = 27 (D) · (-12) + 23 = 11 (E) · (-12) + 18 = 6 (A) · 21 - (-4) = 25 (P) · (-4) + 13 = 9 (H) · 10 - (-11) = 21 (R) · 17 - (-9) = 26 (I) · 1 - (-9) = 10 (O) · 8 - (-12) = 20 (L) · (-13) + 14 = 1 (M)
- Clue 3 (Percentages): "THE VILLAIN SHIVERED WHILE AT THE HIGH CLIFF"20% of 35 = 7 (T) · 50% of 98 = 49 (S) · 10% of 280 = 28 (A) · 25% of 204 = 51 (E) · 25% of 76 = 19 (L) · 50% of 76 = 38 (I) · 5% of 640 = 32 (G) · 25% of 176 = 44 (H) · 50% of 36 = 18 (N) · 40% of 130 = 52 (F) · 50% of 60 = 30 (V) · 50% of 18 = 9 (D) · 50% of 68 = 34 (W) · 20% of 25 = 5 (R) · 50% of 82 = 41 (C)
- Clue 4 (Order of operations): "A CANVAS PITH HELMET WAS LEFT IN THE MUD"12 × 4 - 3 = 45 (A) · 86 + 3 × 2 = 92 (C) · 11 × 12 - 22 = 110 (P) · 10 + 2 × 6 = 22 (E) · 72 + 3 × 3 = 81 (W) · 55 + 7 × 9 = 118 (N) · 12 + 5 × 3 = 27 (H) · 8 + 5 × 7 = 43 (S) · 7 + 2 × 2 = 11 (U) · 12 × 11 - 23 = 109 (F) · 3 + 3 × 2 = 9 (D) · 93 + 6 × 4 = 117 (T) · 10 × 9 - 11 = 79 (V) · 11 × 11 - 22 = 99 (M) · 48 + 5 × 6 = 78 (I) · 10 × 9 - 5 = 85 (L)
- Clue 5 (Two-step equations): surviving statement (box 7) → Wyatt2x + 8 = 10, x = 1 · 3x + 8 = 23, x = 5 · 4x + 3 = 35, x = 8 · 5x + 11 = 56, x = 9 · 3x + 1 = 7, x = 2 · 6x + 3 = 69, x = 11 · 3x + 7 = 43, x = 12 · 2x + 1 = 21, x = 10 · 5x + 8 = 23, x = 3 · 3x + 8 = 26, x = 6 · 4x + 10 = 26, x = 4
About this mystery
- Grade level
- Grade 7 math
- Math topics
- Multiplication, Integers, Percentages, Order of operations, Two-step equations
- Reading level
- grades 7-9
- Theme
- The Lost Idol of El Dorado — set in The Whispering Canopy of the Amazon
- Format
- Interactive online & printable worksheet with answer key
- Solution
- One unique, verified culprit among 21 suspects