What's the area of a rectangle whose perimeter is 30 cm and the longest side is 4 times longer than the shortest?
2 L + 2 w = 30
L = 4 w
========================
2(4 w) + 2 w = 30
10 w = 30
w = 3
so
L = 12
and
A = 3 * 12 cm^2
L = 4 w
========================
2(4 w) + 2 w = 30
10 w = 30
w = 3
so
L = 12
and
A = 3 * 12 cm^2