Which equation could be used to solve problems involving the relationships between the angles?
A) 90 + (8a + 9) = (11 + 2a)
B) 90 − (8a + 9) = (11 + 2a)
C) (11 + 2a) − 90 = (8a + 9)
D) (8a + 9) − (11 + 2a) = 90
