The length of a rectangle is three times it's width. If the perimeter of the rectangle is 40m, find its area

Answer: let the width of the rectangle be x m then the length would be 3x m.

as perimeter = p = 2 (l+b)

40 = 2 (3x+x)

40 = 8x

x=40/8=5m

width = 5m and length = 15m

area = length x breadth

a = 5*15 = 75metresquare