The length of the rectangle is 30 cm and the area is 600 cm2. Calculate the perimeter of this rectangle.

First of all, we find the width of the rectangle, provided that its length is 30 cm and its area = 600 cm².
Let’s express it from the formula:

S = a * b. To find the second factor, divide the product by the first:

b = S: a = 600: 30 = 20 cm.

The perimeter of such a figure, the opposite sides of which are equal, is calculated by the formula:
P = 2a + 2b = 2 * 30 + 2 * 20 = 60 + 40 = 100 cm.