What's the area of a rectangle whose perimeter is 30 cm and the longest side is 4 times longer than the shortest?

Answer 1

2 L + 2 w = 30

L = 4 w

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2(4 w) + 2 w = 30

10 w = 30

w = 3
so
L = 12
and
A = 3 * 12 cm^2