A,B,D,F
Reasoning, the height should be parallel to the base.
Answer
12.56.. I think
umm you haven't said which part of the circles is shaded but I assumed that it's the gap between the two circles

A = P + I
2a = a + PTR/100
2a = a + 5aT/100
2a = a(1+T/20)
2=1+T/20
T=20 yrs