The perimeter of a shape is the total length of the border of the shape
s + 6 + s + 6 + s + s + 2s = 102
6s + 6 = 102
6s = 102 - 6
6s = 96
s = 96 ÷ 6
s = 16
The length of each side is
s + 6 = 16 + 6 = 22
s + 6 = 16 + 6 = 22
s = 16
s = 16
2s = 2 × 16 = 32