SOLUTION: John drove southeast from Albuquerque to Roswell and then south to Carlsbad. He averaged 75 mph along the route from Albuquerque to Roswell and averaged 70 mph from Roswell to Carl

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Question 360684: John drove southeast from Albuquerque to Roswell and then south to Carlsbad. He averaged 75 mph along the route from Albuquerque to Roswell and averaged 70 mph from Roswell to Carlsbad. He covered the entire 220 miles in 3 hours. How long did he take to drive from Albuquerque to Roswell?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
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John drove southeast from Albuquerque to Roswell and then south to Carlsbad.
He averaged 75 mph along the route from Albuquerque to Roswell
and averaged 70 mph from Roswell to Carlsbad.
He covered the entire 220 miles in 3 hours.
How long did he take to drive from Albuquerque to Roswell?
:
Let t = travel time from A to R
then
(3-t) = travel time from R to C
:
Write a distance equation; dist = speed * time
:
A-R dist + R-C dist = 220 miles
75t + 70(3-t) = 220
75t + 210 - 70t = 220
75t - 70t = 220 - 210
5t = 10
t = 2 hrs from A to R
:
:
Check solution by finding the total dist
R to C time 3 - 2 = 1 hr
2(75) + 1(70) = 220 mi