Length of a rectangle is three times its breadth. Perimeter of the rectangle is 40cm. Find its length and width.

Given:

Length, l = 3 × Breadth, b

Perimeter of rectangle = 2 × (l + b)

2 × (3b + b) = 40

2 × 4b= 40

8b = 40

b = 5 cm

Length, l = 3 × 5

Length = 15 cm

Breadth = 5 cm