Answer: 36
Explanation:
The top and bottom of the parallelogram both have lengths of 8.
To determine the length of the parallel diagonal sides, form a right triangle using the left side of the parallelogram as its hypotenuse (in red in my diagram below).
The right triangle has legs of length 6 and 8, so the length of the hypotenuse (c) is:
6^2 + 8^2 = c^2
36 + 64 = c^2
100 = c^2
c = 10
Thus the two diagonal sides of the parallelogram must both have a length of 10, so the perimeter of the parallelogram is 8 + 10 + 8 + 10 = 36.