What it looks like
2x + 4 = 10
x was multiplied by 2. Then 4 was added. You need two spells to undo them.
Undo the adding or subtracting first. Then undo the multiplying.
Worked example 1
2x + 4 = 10
Subtract 4 from both sides
2x = 6
Divide both sides by 2
x = 3
Check it: 2 times 3 is 6. Then 6 + 4 is 10. It works.
Worked example 2
4x − 8 = 12
Add 8 to both sides
4x = 20
Divide both sides by 4
x = 5
Check it: 4 times 5 is 20. Then 20 − 8 is 12.
The most common mistake
Dividing first, and only dividing part of a side.
Not this
2x + 4 = 10, halve the 2x and the 10 but not the 4
x + 4 = 5, so x = 1
But 2 times 1, add 4, is 6, not 10.
This
2x + 4 = 10, subtract 4 first, then divide by 2
x = 3
Dividing a side means dividing everything on it. Subtracting first leaves less to divide.
In the game
You meet these puzzles in the Volcano Forge.