Question

The length of a rectangle is five times its width.

If the perimeter of the rectangle is 72 cm, find its area.

Answer 1

180 cm²

Explanation:

x = length

y = width

perimeter of a rectangle is the sum of all sides, so, 2×length plus 2×width.

x = 5y

72 = 2x + 2y

using the first equation as substitute in the second equation

72 = 2×(5y) + 2y = 10y + 2y = 12y

y = 6 cm

x = 5y = 5×6 = 30 cm

area = x × y = 30 × 6 = 180 cm²