Find the length of the rectangle if its perimeter is 64 cm and width is 8 cm.

P = (a + b) * 2,
where P is the perimeter of the rectangle, a is the length of the rectangle, b is the width of the rectangle.
In order to find the length of a rectangle, you need:
a = Р / 2 – b, substituting the known values into the formula, we get:
a = 64/2 – 8;
a = 24 (cm) – the length of the rectangle.
Having done the check, we get:
64 = (24 + 8) * 2;
64 = 32 * 2;
64 = 64
Answer: 24 centimeters.