If the length of a rectangle increases by 20%, and the width decrease by 20%, by what percent does the area change?
A 20% increase has a multiplier of 1.2
A 20% decrease has a multiplier of 0.8
(1.2L)x(0.8W) = (1.2x0.8)LW = (0.96)LW
The factor 0.96 is the multiplier for a 4% decrease, so the area decreased by 4%.