Answer:
225
Explanation:
If you move the bottom triangle up (as shown in the picture) it's not actually a square. And they haven't provided you with enough information to solve for anything unless there are still unknown values. You would need to know at least another leg length or angle. If they want the actual value in square millimeters, my best guess is that it's supposed to be a square. Since a square has sides of the same length, the area would be 15 * 15 which is 225.