Equations with brackets
Expand the bracket first, or divide the whole equation by the number outside it, then solve as usual.
A worked example
Solve 9(x + 2) = 72. Divide both sides by 9 to get x + 2 = 8, then subtract 2, so x = 6.
The mistake people actually make
The number outside a bracket multiplies every term inside, not just the first. With a minus sign outside, both signs inside flip.