No idea, i would've done it the easiest way which is to find the area of a rectangle and take away the areas of the two smaller triangles around the original triangle.
The area of the triangle in the attachment has to be found.
It is not stated in the question what kind of a triangle it is nor are there any angles given.
I believe that there is information that has been left out of the diagram to solve this question (This is a question in a maths...