How long did the car travel at each speed?

Question

A car went 372 miles in 6 hours, traveling part of the time at 55 miles per hour and part of the time at 70 miles per hour. How long did the car travel at each speed?

Answer 1

distance = rate*time

 

In this case:  distance = (time at 55mph)(55) + (time at 70 mph)(70)

 

372 = 55t + 70(6-t)

 

55t + 420 - 70t = 372

 

Solving for t will give the time spent at 55 mph

Then 6-t will be the time spent driving at 70 mph