Question

if the length of the rectangle is twice the width, and the perimeter of the rectangle is 30cm. what is the length and width of the rectangle ?

Answer 1

L=2W

P=2(L+W), using L from above in this equation gives us:

P=2(2W+W)

P=2(3W)

3W=P/2

W=P/6, we are told that P=30cm so

W=30/6

W=5 cm, and since L=2W

L=10 cm

Answer 2

Let the length be l and the width be w. Then l=2w. Since the perimeter is 30, 2(l+w)=3, 2(2w+w)=30, 6w=30. Therefore the width is 5 and the length is 10.