Answer:
51
Explanation:
the vertical side is 12 units, the bottom horizontal side is 15 units.
To help find the funky side's length, you've gotta first pretend that the shape is a rectangle. So, make the top horizontal line the same length as the bottom one, then draw the new vertical line in between the two to make a rectangle.
The slanted line makes it look like you've made a triangle, kind of. Anyways, you've also made a right triangle. I don't know if you've studied the Pythagorean Theorem yet, but the new section of the "rectangle" equals 9 (also the top leg of the triangle) and the new side you've drawn equals 12 units, so according to the Pythagorean theorem, 9^2 + 12^2 =225^2. You need to get the square root of 225 which is 15, and 15 is the trapezoid's funky side. So, all in all, the total perimeter would be 12+15+15+9 = 51.