The perimeter of a rectangular plot is 90 m. Its width is 20 m. What is its area?

The perimeter of a rectangle whose opposite sides are equal is calculated by the formula:
P = 2a + 2b. Provided that this value for a section of this shape is 90 m, and its width = 20 m, we express the length:
a = (P – 2b): 2 = (90 – 2 * 20): 2 = (90 – 40): 2 = 50: 2 = 25 m.
Let’s find the area of this site using the formula:
S = a * b = 25 * 20 = 500 m².