You would split up the two shapes separately, hopefully on pen and paper, and label all sides. Since you don't have a height for the triangle, and it is lined up to the rectangle, carry over the 12 inches to the hypotenuse (the long) side of the triangle. So the width and height of the triangle would be 8x12. The rectangle would be 16x12. Multiply both dimensions together, the area of the triangle being 96 and the rectangle being 192. Add the two shape's areas together for your compound shape, making it 288.