The width of a rectangular piece of land is 15 m shorter than its length, the perimeter is 126 m. Calculate its sides.

The opposite sides of a rectangle are equal and its perimeter is calculated by the formula:

P = 2a + 2b.

Provided that this value for such a figure is 126 m, and the length is 15 m greater than the width, we compose the equation:

2x + 2 * (x + 15) = 126. Let’s expand the brackets:

2x + 2x + 30 = 126. Let’s perform operations with the coefficients of the variable on the left side of the equation, and transfer the number to the right, while the sign in front of it changes to the opposite:

4x = 126 – 30.

4x = 96.

x = 96: 4 = 24.

Therefore, b = 24 m, a = 24 + 15 = 39 m.