The Rath Family drove to the beach at 85 kmph. They returned by a different route at 70 kmph. Each trip took the same time, but the return trip was 30 km shorter. How long did each trip take?
D/85 =[D-30]/70, solve for D
D=170km - outgoing distance to the beach
170-30 =140 km-return distance
170/85 =2 hours - time taken to get to the beach.
[170 - 30] / 70 =2 hours - return time.