When the length of a rectangle is increased by 20% and the width increased by 10%, by what percent is the area increased?
original area = L * W
new length = L + 20% * L = L + 0.2L = 1.2L
new width = W + 10% * W = W + 0.1W = 1.1W
new area = 1.2L * 1.1W
new area = 1.2 * 1.1 * L * W
new area = 1.32 * L * W
new area = 1.32 * original area
new area = (1 + 0.32) * original area
new area = original area + 0.32 * original area
new area = original area + 32% * original area
The new area is the original area increased by 32% of the original area.