<p>Well, you can use Pythagorean theorem to get the side JI as 5, and then use one half base x height to get the area of the triangle, which is 30. Looking at the drawing, I couldn’t tell much of this, but it gave the correct answer, so I did this. Assume that the base of the parallelogram is also 13. Then the area of a parallelogram is simply base x height, or 12 x 13, which is 156. That plus the area of the triangle, 30, gives 186. Does that help?</p>