The side of the square is 12 cm. Find the width of a rectangle with the same perimeter and a length of 15 cm.

We define the perimeter of a square, which is equal to the sum of all its sides using such an arithmetic operation as multiplication:

12 x 4 = 48 cm.

Let the width of the rectangle be x cm.Then, according to the above conditions of the problem, we will compose and solve using such arithmetic operations as division and subtraction the following equation:

(x + 15) * 2 = 48,

x + 15 = 48: 2,

x + 15 = 24,

x = 24 – 15,

x = 9 cm.

Let’s check the correctness of the solution:

(9 + 15) * 2 = 24 * 2 = 48 cm.

Answer: the width of this rectangle was 9 cm.