Problem 2 seems to have two ways of going about it.
Way 1
Assume the whole shape is a triangle and the unshaded region is a trapezoid. Subtract the trapezoid's area from the triangle's area.
Way 2
Assume both shaded regions are triangles. Add the shaded triangles' areas.
I'm fairly certain at least Triangle 1's area is correct because finding the area of the trapezoid containing Triangle 1 and the unshaded trapezoid yields the same area as when combining the area of Triangle 1 determined in Way 2 and the area of the trapezoid determined in Way 1: A=(a+b)*h/2 = ((12+13)+15)*11/2 = 220.
Question
Why doesn't Way 2 provide the correct answer?
Best Answer
It's the second solution which is correct, and the first one is wrong!
The error hides in the assumption the whole figure is a triangle. If it was, the big triangle would be similar to the smaller one on the right side, hence the proportion would hold $$\frac{12+13}{11+21}=\frac{15}{21}$$ However, it does not, as $$\frac{12+13}{11+21}=0.78125 > 0.7142857 \approx \frac{15}{21}$$ and the big figure is a concave quadrangle.