Algebra Codebreaker Riddles - KS3 Maths Worksheets | Teaching ... - Free Printable

Let’s solve each equation step by step. We’ll find the value of x for each letter, then use those numbers to fill in the riddle boxes and answer the joke.

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Step 1: Solve all equations

We go row by row:

Row 1:

- A: x + 2 = 9 → x = 9 - 2 = 7
- B: 2x = 8 → x = 8 ÷ 2 = 4
- C: 3x + 1 = 10 → 3x = 9 → x = 3
- D: 7 - 2x = 5 → -2x = 5 - 7 = -2 → x = (-2) ÷ (-2) = 1
- E: x + 2 = -1 → x = -1 - 2 = -3
- F: x + 5 = 30 → x = 30 - 5 = 25
- G: 4x - 2 = 38 → 4x = 40 → x = 10
- H: 3x - 2 = 16 → 3x = 18 → x = 6
- I: 2x - 4 = 30 → 2x = 34 → x = 17

Row 2:

- J: 5x + 1 = -9 → 5x = -10 → x = -2
- K: 21 - 2x = 11 → -2x = 11 - 21 = -10 → x = (-10) ÷ (-2) = 5
- L: 5x + 1 = 101 → 5x = 100 → x = 20
- M: 5x + 2 = -48 → 5x = -50 → x = -10
- N: 3x + 1 = -2 → 3x = -3 → x = -1
- O: 10 - x = 1 → -x = 1 - 10 = -9 → x = 9
- P: 5x + 3 = -17 → 5x = -20 → x = -4
- Q: 2x + 5 = 29 → 2x = 24 → x = 12
- R: 12 - x = 17 → -x = 5 → x = -5

Row 3:

- S: 30 - 2x = 8 → -2x = 8 - 30 = -22 → x = (-22) ÷ (-2) = 11
- T: 10 - x = 8 → -x = -2 → x = 2
- U: 3x + 3 = 3 → 3x = 0 → x = 0
- V: 5x + 5 = 45 → 5x = 40 → x = 8
- W: 3x + 6 = 45 → 3x = 39 → x = 13
- X: 50 + 2x = 86 → 2x = 36 → x = 18
- Y: 30 + 6x = -6 → 6x = -36 → x = -6
- Z: 4x = 60 → x = 15

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Now let’s list all answers with their letters:

A=7
B=4
C=3
D=1
E=-3
F=25
G=10
H=6
I=17
J=-2
K=5
L=20
M=-10
N=-1
O=9
P=-4
Q=12
R=-5
S=11
T=2
U=0
V=8
W=13
X=18
Y=-6
Z=15

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Step 2: Fill in the riddle boxes

The riddle says: “Why should you never believe a clock?”

Below are groups of boxes with numbers already filled in — we need to match those numbers to the correct letters (using our solved values), then read the message.

Look at the first group:

Box 1: [17] [2] [11] → I=17, T=2, S=11 → “ITS”

Second group:

[0] [11] [0] [7] [20] [20] [-6] → U=0, S=11, U=0, A=7, L=20, L=20, Y=-6 → “USUALLY”

Third group:

[11] [-3] [3] [9] [-1] [1] → S=11, E=-3, C=3, O=9, N=-1, D=1 → “SECOND”

Fourth group:

[6] [7] [-1] [1] → H=6, A=7, N=-1, D=1 → “HAND”

Fifth group (long one):

[17] [-1] [25] [9] [-5] [-10] [7] [2] [17] [9] [-1] → I=17, N=-1, F=25, O=9, R=-5, M=-10, A=7, T=2, I=17, O=9, N=-1 → “INFORMATION”

Wait — that doesn’t make sense yet. Let’s put it together:

“ITS USUALLY SECOND HAND INFORMATION”

But that’s not quite right. Maybe we misread the grouping?

Actually, looking again — the riddle is probably meant to be read as:

First box set: 17, 2, 11 → I, T, S → “ITS”

Second: 0,11,0,7,20,20,-6 → U,S,U,A,L,L,Y → “USUALLY”

Third: 11,-3,3,9,-1,1 → S,E,C,O,N,D → “SECOND”

Fourth: 6,7,-1,1 → H,A,N,D → “HAND”

Fifth: 17,-1,25,9,-5,-10,7,2,17,9,-1 → I,N,F,O,R,M,A,T,I,O,N → “INFORMATION”

So full phrase: “ITS USUALLY SECOND HAND INFORMATION”

But wait — clocks have “second hands”, and “second-hand information” means unreliable info.

So the joke is: You shouldn’t believe a clock because its information is always “second hand” — which is a pun!

Clocks have a second hand (the needle that counts seconds), and “second-hand” also means not original or trustworthy.

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Final Answer:
Because its information is usually second hand.