The perimeter of a rectangle, is the length of all of the sides of a rectangle added together.
Each rectangle has two equal lengths, and two equal widths. Since we know the length is equal to 14, then the two lengths together would be 28. The width is 12, and the two widths together are 24.
Finally we add the 28 and 24 together to find the total perimeter of 52 centimeters.