Calculate the perimeter of a rectangle whose width is 4 cm, and it is 3 times less than its length.

Let’s find the length of the rectangle:

1) 4 * 3 = 12 (cm) – the length of the rectangle;

The perimeter of a figure is the sum of the lengths of its sides. Since a rectangle has its parallel sides equal to each other, the perimeter of the rectangle is equal to twice the sum of its length and width: p = 2 (a + b).

2) 2 * (4 + 12) = 2 * 16 = 32 (cm)

Answer: The perimeter of the rectangle is 32 cm.