Answer: The answer is 12.5 ft.
Step-by-step explanation: Given that there is a rectangle with ratio of its length to breadth 8 : 5. Also, the longer side of the rectangle is 20 feet. We are to find the length of the shorter side.
Let, '8x' and '5x' be the length and breadth of the rectangle respectively. Since length is the longer side, so we have
Therefore, width, length of the shorter side will be
Thus, the length of the shorter side is 12.5 ft.