One of the sides of the parallelogram is 13.4 cm, and the other is 0.8 cm less than the first side. Find its perimeter.

The condition says that one side of the parallelogram is 13.4 cm long, and it is also known that the other side is 0.8 cm smaller.
In order to find the perimeter of a parallelogram, we will first of all recall the formula for finding the perimeter of a parallelogram:
P = 2 (a + b), where a and b are the lengths of the sides of the parallelogram.
We know the length of one of the sides, let’s calculate the length of the second side:
13.4 – 0.8 = 12.6 cm.
We just have to substitute the values and calculate:
P = 2 (13.4 + 12.6) = 2 * 26 = 52 cm perimeter of the parallelogram.