Find the perimeter of a rectangle whose adjacent sides are 13 millimeters and 17 millimeters.

If the first two adjacent sides of the rectangle are equal: 13 millimeters and 17 millimeters, then it should be concluded that the other two sides of the rectangle are also equal to 13 millimeters and 17 millimeters. Knowing all four sides, subtract the perimeter of the figure. It is equal to the sum of all sides of the rectangle. Let us denote the perimeter by the letter P. Therefore:

P = 13 mm + 17 mm + 13 mm + 17 mm = 30 mm + 30 mm = 60 mm.

Or, in other words, the perimeter of the rectangle is 6 centimeters.