Two-step equations
Undo the addition or subtraction first, then undo the multiplication or division.
A worked example
Solve 4x − 9 = 35. Add 9 to both sides to get 4x = 44, then divide by 4 to get x = 11.
The mistake people actually make
Dividing before the constant has been moved means every term must be divided, which is easy to get wrong. Substitute your answer back to check.