2 busses leave Houston at the same time and travel in opposite directions. 1 bus averages 55 miles per hour and the other bus averages 45 miles per hour. When will they be 400 miles apart?
Speed=distance/time ⇒ distance=speed * time. t=time when the busses are aparted 400 miles. we can suggest this equation: 45 t+55 t=400 100t=400 t=400/100 t=4