Susan drove an average speed of 30 miles per hour for the first 40 miles of a trip then at a average speed of 15 miles/hr for the remaining 40 miles of the trip if she made no stops during the trip what was susan's avg speed in miles/hr for the entire trip	Choose the correct choice from the following
A) 35	B) 20	C) 45	D) 50	E) 55

Rationale: avg . speed = total distance / total time total distance = 80 miles total time = 40 / 30 + 40 / 15 = 4 avg . speed = 20 . answer - b
Answer: B