x on both sides

There is an x on the left and an x on the right.

What it looks like

2x + 3 = x + 7

Gather the x's onto one side first. Subtract the smaller lot of x from both sides. Then solve it like any other puzzle.

In the game, turn on the x button next to the number to cast a spell with x.

Worked example 1

  1. 2x + 3 = x + 7

  2. Subtract x from both sides

  3. x + 3 = 7

  4. Subtract 3 from both sides

  5. x = 4

Check both sides. Left: 2 times 4 is 8, add 3 is 11. Right: 4 + 7 is 11.

They match.

Worked example 2

  1. 5x + 1 = 2x + 10

  2. Subtract 2x from both sides

  3. 3x + 1 = 10

  4. Subtract 1 from both sides

  5. 3x = 9

  6. Divide both sides by 3

  7. x = 3

Check both sides. Left: 5 times 3 is 15, add 1 is 16. Right: 2 times 3 is 6, add 10 is 16.

They match.

The most common mistake

Subtracting plain numbers first and never moving the x.

Not this

2x + 3 = x + 7, subtract 3, then subtract 4

2x − 4 = x

There is still an x on both sides.

This

2x + 3 = x + 7, subtract x from both sides

x + 3 = 7

Only one x is left.

You cannot find x while it is on both sides. Gather it first.

In the game

You meet these puzzles in the Mirror Marsh.

Back to the game