Find the area of the composite figure

You split it into a triangle and a rectangle. The rectangle’s area is 12x16=192. For the triangle, you have to find the length of the b side. You already know a and c so 12^2 + b^2=15.5^2. Solve it algebraically to get b=9. So the triangle has an area of (12x9)/2=54. So the total area is 192+54=246cm^2.