The width of the rectangle is 4 whole 1/5 cm, which is 1/2 of its length. Find the perimeter of the rectangle.

1. Find the length of the rectangle. From the condition of the problem it can be seen that the width of the rectangle is half its length, therefore:
4 1/5 x 2 = 21/5 x 2 = 42/5 = 8 2/5 (cm).
2. Knowing the length of the rectangle, we find its perimeter (P = (a + b) x 2
(4 1/5 + 8 2/5) x 2 = 12 3/5 x 2 = 63/5 x 2 = 126/5 = 25 1/5 (cm).
Answer: the perimeter is 25 1/5 cm.