All side lengths are given in terms of the shortest side, so let x = length of the shortest side.
Shortest side = x
Second side = x + 4
Third side = 2x - 4
perimeter = shortest side + second side + third side
x + x + 4 + 2x - 4 = 52
4x = 52
x = 13
The shortest side is x, so it is 13 ft long.
x + 4 = 13 + 4 = 17
The second side is 17 ft long.
2x - 4 = 2(13) - 4 = 26 - 4 = 22
The third side is 22 ft long.
Answer: 13 ft, 17 ft, 22 ft