The perimeter of the rectangle is 56 cm and its length is 7 cm. Find the area of the rectangle.

The perimeter of the rectangle is 56 cm and its length is 7 cm. Find the area of the rectangle. If you know one hundred, the side is also 7 cm.

P = 2 * (a + b), we know the perimeter and one side from the problem conditions, substitute the numerical values and find the second side.
56 = 2 * (7 + b);
14 + 2b = 56;
2b = 56-14;
2b = 42;
b = 42/2;
b = 21 (cm) – the second side of the rectangle.
Find the area of the rectangle:
S = a * b;
S = 7 * 21 = 147 (cm2)
Answer: 147 cm2 area of a rectangle