The length of the rectangle is 7 cm. Find its width if you know that the perimeter of the rectangle is 22 cm.

Length (a) – 7 cm;

Width (b) -? cm;

Perimeter (Ppr.) – 22 cm.

The perimeter of any polygon is the sum of the lengths of all its sides.

A rectangle has opposite sides equal in pairs, so its perimeter is calculated by the formula:

Ppr. = (a + b) * 2.

Let us express the width b from this formula:

a + b = Ppr. / 2;

b = (Ppr. / 2) – a.

Knowing from the condition the values of the length and perimeter, we calculate the value of the desired width:

b = (Ppr. / 2) – a = (22/2) – 7 = 11 – 7 = 4 (cm).

Answer: The width of the rectangle is 4 cm.