A car traveled 75% of the way from town A to town B at an average speed of 60 miles per hour. The car travels at an average speed of S miles per hour for the remaining part of the trip. The average speed for the entire trip was 40 miles per hour. What is S ?
Answers:
A) 10  B) 20  C) 25  D) 30  E) 37.5

Rationale: total distance = 100 miles ( easier to work with % ) 75 % of the distance = 75 miles 25 % of the distance = 25 miles 1 st part of the trip → 75 / 60 = 1.25 2 nd part of the trip → 25 / s = t total trip → ( 75 + 25 ) / 40 = 1.25 + t » 100 / 40 = 1.25 + t » 2.5 = 1.25 + t » t = 1.25 back to 2 nd part of the trip formula : 25 / s = 1.25 » s = 20 ans b
Answer: B