The perimeter of a rectangle is 30 cm. What is its width if it is 1 cm less than its length?

From the condition it is known that the perimeter of the rectangle is 30 cm. In order to find what its width is equal to, if it is 1 cm less than the length, we compose and solve the equation.

To compose the equation, we will use the formula for finding the perimeter of a rectangle:

P = 2 (a + b);

We introduce the variable x cm, denoting the width of the rectangle, then the length can be written as (x + 1) cm.

Let’s substitute all values in the formula:

2 (x + x + 1) = 30;

x + x + 1 = 30: 2;

2x + 1 = 15;

2x = 15 – 1;

2x = 14;

x = 14: 2;

x = 7 cm rectangle width, 7 + 1 = 8 cm rectangle length.