SOLUTION: A car was driven for 2 hours part of the time at 40 miles per hour and the rest of the time at 60 miles per hour. the total distance was 90 miles . how long did the car travel at e

Algebra ->  Absolute-value -> SOLUTION: A car was driven for 2 hours part of the time at 40 miles per hour and the rest of the time at 60 miles per hour. the total distance was 90 miles . how long did the car travel at e      Log On


   

Question 460300: A car was driven for 2 hours part of the time at 40 miles per hour and the rest of the time at 60 miles per hour. the total distance was 90 miles . how long did the car travel at each speed.
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
A car was driven for 2 hours part of the time at 40 miles per hour and the rest of the time at 60 miles per hour.
the total distance was 90 miles . how long did the car travel at each speed.
:
Let x = distance at 40 mph
then
(90-x) = distance at 60 mph
:
Write a time equation; time = dist/speed
:
4o mph time + 60 mph time = 2 hrs
x%2F40 + %28%2890-x%29%29%2F60 = 2
Multiply by 120
120*x%2F40 + 120*%28%2890-x%29%29%2F60 = 120(2)
Cancel the denominators and you have:
3x + 2(90-x) = 240
3x + 180 - 2x = 240
3x - 2x = 240 - 180
x = 60 mi at 40 mph
then
90-60 = 30 mi at 60 mph
:
Find the times at each speed
60/40 = 1.5 hr at 40 mph
30/60 = .5 hrs at 60 mph
--------------
total 2 hrs