Answer
H. $26$
Work Step by Step
1) Find the perimeter of the square which is P=4(2x) = 8x (side length is 2x)
2) Find the perimeter of the triangle which is the sum of the lengths P= 3x + 4x - 3 +16= 7x +13
3) Then since the lengths are equal, combine them giving you 7x + 13=8x
4) To solve for x, simplify like terms giving you 13=x
5) And since the lengths are equal, substitute the 13 into the 2(x).
6) Giving you 26, which is answer H