Fine, no one wants to answer. I'll answer my own question. The answer is 68 units.
Hey I want to answer!
perimeter = side + side + side + side
All the sides are congruent, so
perimeter = 4(side)
The diagonals bisect each other, so the legs of the little triangles are 16/2 and 30/2.
Use pythagorean theorem to find length of one side.
82 + 152 = side2
√(289) = side
17 = side
perimeter = 4(17)
perimeter = 68