If the average (arithmetic mean) of (2a+16) and (3a-8) is 89, what is the value of a?	Choose the correct choice:  A) 25  B) 30  C) 28  D) 34  E) 42

Rationale: "( ( 2 a + 16 ) + ( 3 a - 8 ) ) / 2 = ( 5 a + 8 ) / 2 = 89 a = 34 the answer is d ."
Answer: D