🌊 Cats, MermaidsGrade 7Reading: grades 7-9IntegersPercentagesOrder of operationsExponentsTwo-step equations

The Mystery of the Sunken Catnip

The Grand Pearl Keeper of Meow-lantis woke up to find the sacred Golden Catnip Kelp gone! A mysterious rogue mer-cat was spotted fleeing the scene. We need you to decode the evidence, trace the culprit, and save the ocean ecosystem.

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	Primary Magic	Secondary Gear	Swim Style	Tail Fin Color	Vulnerability
Oliver	Jellyfish shock	Kelp lasso	Left-finned stroke	Abyssal blue	High pitches
Milo	Coral craft	Pearl wand	Right-finned stroke	Abyssal blue	High pitches
Toby	Coral craft	Shell flute	Right-finned stroke	Coral pink	Tickly seaweed
Ziggy	Coral craft	Shell flute	Left-finned stroke	Seafoam green	High pitches
Ariel	Jellyfish shock	Pearl wand	Right-finned stroke	Seafoam green	Bright spotlights
Jasper	Bubble shield	Kelp lasso	Right-finned stroke	Seafoam green	High pitches
Bubbles	Whirlwind claw	Crab shield	Right-finned stroke	Coral pink	Tickly seaweed
Marina	Coral craft	Crab shield	Right-finned stroke	Coral pink	High pitches
Selena	Whirlwind claw	Shell flute	Right-finned stroke	Coral pink	High pitches
Felix	Whirlwind claw	Pearl wand	Right-finned stroke	Coral pink	Tickly seaweed
Coralia	Echo purr	Crab shield	Right-finned stroke	Coral pink	Tickly seaweed
Luna	Whirlwind claw	Kelp lasso	Left-finned stroke	Abyssal blue	Bright spotlights
Simba	Bubble shield	Pearl wand	Right-finned stroke	Abyssal blue	Tickly seaweed
Whisker	Echo purr	Crab shield	Right-finned stroke	Seafoam green	High pitches
Pearl	Echo purr	Crab shield	Right-finned stroke	Seafoam green	Tickly seaweed
Barnaby	Jellyfish shock	Starfish crown	Left-finned stroke	Coral pink	Tickly seaweed
Clawdia	Bubble shield	Crab shield	Left-finned stroke	Coral pink	Bright spotlights
Poseidon	Echo purr	Starfish crown	Right-finned stroke	Abyssal blue	Bright spotlights
Salty	Coral craft	Pearl wand	Right-finned stroke	Abyssal blue	Tickly seaweed
Muriel	Bubble shield	Kelp lasso	Right-finned stroke	Coral pink	Tickly seaweed
Cleo	Whirlwind claw	Crab shield	Left-finned stroke	Coral pink	Bright spotlights

Clue 1

Integers

To trace the suspect's escape route, we must analyze the depth logs. A patrol submersible registered rapid changes in altitude, diving below sea level and rising near thermal vents. Help us calculate the final integer depth value to unlock the first evidence locker.

Solve each problem to learn its letter. Then write that letter in every box that shows the same number, and read the secret clue.

(-15) + 45 =T

21 - (-8) =O

4 - (-14) =A

2 - (-14) =N

(-5) + 33 =D

(-15) + 30 =U

(-14) + 27 =V

(-14) + 23 =F

13 - (-8) =E

(-3) + 6 =H

(-12) + 18 =L

2 - (-2) =S

(-10) + 24 =I

0/13 letters found

Clue 2

Percentages

The palace vault doors are locked with a hydro-pressure seal that requires calculating the exact percentage of water flow diversion. Solve the percentage puzzle to open the secondary files.

Solve each problem to learn its letter. Then write that letter in every box that shows the same number, and read the secret clue.

25% of 80 =T

10% of 260 =C

10% of 570 =N

50% of 26 =G

10% of 180 =A

5% of 200 =H

25% of 44 =D

60% of 75 =E

5% of 320 =O

60% of 45 =S

10% of 290 =I

50% of 24 =W

50% of 66 =F

10% of 460 =R

50% of 84 =M

5% of 460 =K

50% of 34 =U

25% of 232 =P

0/18 letters found

Clue 3

Order of operations

Our ancient hydro-puzzles require solving multi-step equations using the correct sequence of operations. Solve this sequence to activate the deep-sea sonar system and pin down the suspect's movement.

Solve each problem to learn its letter. Then write that letter in every box that shows the same number, and read the secret clue.

102

7 × 10 - 28 =T

24 + 2 × 2 =U

11 × 5 - 22 =H

3 × 12 - 1 =K

42 + 2 × 6 =W

10 × 12 - 18 =E

68 + 4 × 7 =S

40 + 2 × 2 =I

12 × 10 - 23 =R

8 × 10 - 8 =F

9 × 8 - 23 =C

39 + 9 × 5 =D

11 × 4 - 15 =Y

7 × 11 - 1 =L

6 × 12 - 29 =A

8 × 11 - 2 =P

0/16 letters found

Clue 4

Exponents

The stolen catnip kelp contains spores that multiply exponentially when exposed to deep-sea light. To prevent a massive ecological overgrowth, we must calculate the exponent value of the spreading spores.

Solve each problem to learn its letter. Then write that letter in every box that shows the same number, and read the secret clue.

100

196

121

216

361

343

125

256

216

128

121

256

216

361

125

196

343

125

361

196

10^2 =W

7^2 =T

16^2 =I

2^5 =O

2^3 =D

11^2 =F

19^2 =C

8^2 =S

14^2 =E

6^3 =N

2^7 =K

7^3 =R

5^3 =A

3^2 =U

6^2 =P

5^2 =L

0/16 letters found

Clue 5

Two-step equations — the last clue

We found a set of balance scales used by the suspect to weigh stolen pearls. By setting up a two-step equation representing the weights of the shells and the pearls, we can balance the scales and reveal the final clue.

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

3x + 5 = 8, x = ?

4x + 9 = 49, x = ?

5x + 9 = 19, x = ?

6x + 12 = 84, x = ?

6x + 2 = 50, x = ?

3x + 4 = 16, x = ?

3x + 4 = 22, x = ?

5x + 7 = 62, x = ?

3x + 5 = 14, x = ?

4x + 12 = 32, x = ?

6x + 3 = 45, x = ?

Step 2 — cross out the sentence with each answer

1.The villain plundered the pearl vault, then vanished into the deep trench.

2.The villain swiped the royal catnip, then escaped in a bubble ship.

3.The villain pilfered the golden clam, then hid inside the dark shipwreck.

4.The villain snatched the glowing coral, then escaped in a bubble ship.

5.The villain pilfered the golden clam, then vanished into the deep trench.

6.The villain pinched the sacred seaweed, then vanished into the deep trench.

7.The villain swiped the royal catnip, then hid inside the dark shipwreck.

8.The villain snatched the glowing coral, then vanished into the deep trench.

9.The villain snatched the glowing coral, then swam through the kelp forest.

10.The villain swiped the royal catnip, then vanished into the deep trench.

11.The villain plundered the pearl vault, then escaped in a bubble ship.

12.The villain pilfered the golden clam, then swam through the kelp forest.

Solve it

Name the culprit

Choose the one suspect left standing.

Answer Key — The Mystery of the Sunken Catnip

Culprit: Muriel (Bubble shield · Kelp lasso · Right-finned stroke · Coral pink · Tickly seaweed)

Clue 1 (Integers): "THE VILLAIN DOES NOT USE A SHELL FLUTE"
(-15) + 45 = 30 (T) · 21 - (-8) = 29 (O) · 4 - (-14) = 18 (A) · 2 - (-14) = 16 (N) · (-5) + 33 = 28 (D) · (-15) + 30 = 15 (U) · (-14) + 27 = 13 (V) · (-14) + 23 = 9 (F) · 13 - (-8) = 21 (E) · (-3) + 6 = 3 (H) · (-12) + 18 = 6 (L) · 2 - (-2) = 4 (S) · (-10) + 24 = 14 (I)
Clue 2 (Percentages): "THE SUSPECT SWIMS WITH A RIGHT FINNED STROKE"
25% of 80 = 20 (T) · 10% of 260 = 26 (C) · 10% of 570 = 57 (N) · 50% of 26 = 13 (G) · 10% of 180 = 18 (A) · 5% of 200 = 10 (H) · 25% of 44 = 11 (D) · 60% of 75 = 45 (E) · 5% of 320 = 16 (O) · 60% of 45 = 27 (S) · 10% of 290 = 29 (I) · 50% of 24 = 12 (W) · 50% of 66 = 33 (F) · 10% of 460 = 46 (R) · 50% of 84 = 42 (M) · 5% of 460 = 23 (K) · 50% of 34 = 17 (U) · 25% of 232 = 58 (P)
Clue 3 (Order of operations): "THE SUSPECT FEARS TICKLY SEAWEED"
7 × 10 - 28 = 42 (T) · 24 + 2 × 2 = 28 (U) · 11 × 5 - 22 = 33 (H) · 3 × 12 - 1 = 35 (K) · 42 + 2 × 6 = 54 (W) · 10 × 12 - 18 = 102 (E) · 68 + 4 × 7 = 96 (S) · 40 + 2 × 2 = 44 (I) · 12 × 10 - 23 = 97 (R) · 8 × 10 - 8 = 72 (F) · 9 × 8 - 23 = 49 (C) · 39 + 9 × 5 = 84 (D) · 11 × 4 - 15 = 29 (Y) · 7 × 11 - 1 = 76 (L) · 6 × 12 - 29 = 43 (A) · 8 × 11 - 2 = 86 (P)
Clue 4 (Exponents): "WE FOUND CORAL PINK FIN SCALE TRACES"
10^2 = 100 (W) · 7^2 = 49 (T) · 16^2 = 256 (I) · 2^5 = 32 (O) · 2^3 = 8 (D) · 11^2 = 121 (F) · 19^2 = 361 (C) · 8^2 = 64 (S) · 14^2 = 196 (E) · 6^3 = 216 (N) · 2^7 = 128 (K) · 7^3 = 343 (R) · 5^3 = 125 (A) · 3^2 = 9 (U) · 6^2 = 36 (P) · 5^2 = 25 (L)
Clue 5 (Two-step equations): surviving statement (box 9) → Muriel
3x + 5 = 8, x = 1 · 4x + 9 = 49, x = 10 · 5x + 9 = 19, x = 2 · 6x + 12 = 84, x = 12 · 6x + 2 = 50, x = 8 · 3x + 4 = 16, x = 4 · 3x + 4 = 22, x = 6 · 5x + 7 = 62, x = 11 · 3x + 5 = 14, x = 3 · 4x + 12 = 32, x = 5 · 6x + 3 = 45, x = 7

About this mystery

Grade level: Grade 7 math
Math topics: Integers, Percentages, Order of operations, Exponents, Two-step equations
Reading level: grades 7-9
Theme: The Mystery of the Sunken Catnip — set in Meow-lantis
Format: Interactive online & printable worksheet with answer key
Solution: One unique, verified culprit among 21 suspects

More free printable math mysteries

7th grade worksheets Percentages worksheets Exponents worksheets Order of operations worksheets Integers worksheets Two-step equations worksheets All worksheets →

The Great Whisker City Heist

Grade 7

The Mystery of the Golden Mask

Grade 7

The Cosmic Redstone Sabotage

Grade 7

The Sky-Island Compass Caper

Grade 7