Question

Two school buses leave the same school at the same time, but are headed in opposite directions. One bus traveled 45 miles per hour and the other bus traveled 40 miles per hour.

How long until the buses are 170 miles apart?

Answer 1

40 mph: 4 hours 15 minutes

45 mph: 3 hours 46 minutes 40 seconds

Explanation:

The rate of separation = 45 + 40 = 85 mph

speed = distance / time

85 = 170 / t

t= 170/85 hour

Answer 2

2 hours

Explanation:

45x + 40x = 170

85x = 170

x = 2