Question

Two buses leave houston at the same time and travel in opposite directions. one bus averages 55 miles per hour, and the other bus averages 45 miles per hour. when will the buses be 400 miles apart? the second step in solving a word problem is to define the variables.

Answer 1

Basically, this is as if ONE bus is traveling 100 miles per hour (55 mph + 45 mph).
How long does it take that one bus to travel 400 miles?
400 miles  / 100 miles per hour = 4 hours