You are given two rectangles with equal perimeters. The first rectangle is 12 cm long and 7 cm wide.

You are given two rectangles with equal perimeters. The first rectangle is 12 cm long and 7 cm wide. The second rectangle is 5 cm wide. Find the length of the second rectangle.

The solution of the problem.

1. Let’s calculate the perimeter of the first rectangle.

(12 cm + 7 cm) * 2 = 19 cm * 2 = 38 cm.

2. Find the perimeter of the second rectangle.

38 cm.

3. Let’s denote by x the length of the second rectangle.

4. Let’s compose and solve the equation.

(x + 5) * 2 = 38;

x + 5 = 19;

x = 19 – 5;

x = 14.

Answer. The second rectangle is 14 centimeters long.