Question

Two buses leave Houston at the same time and travel in opposite directions. One bus averages 55 mi/hr and the other bus averages 45 mi/hr. When will the buses be more than 400 miles apart?

Answer 1

If they are traveling in different directions then you add up the two mi/hr then whatever you have to multiply the sum by is the number of hours. By the way the sender is 4 hours.