SOLUTION: Sheri drove southeast from Albuquerque to Roswell and then south to Carlsbad. She averaged 75 mph along the route from Albuquerque to Roswell and averaged 70 mph from Roswell to Ca

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: Sheri drove southeast from Albuquerque to Roswell and then south to Carlsbad. She averaged 75 mph along the route from Albuquerque to Roswell and averaged 70 mph from Roswell to Ca      Log On


   

Question 258028: Sheri drove southeast from Albuquerque to Roswell and then south to Carlsbad. She averaged 75 mph along the route from Albuquerque to Roswell and averaged 70 mph from Roswell to Carlsbad. She covered the entire 220 miles in 3 hours. How long did she take to drive from Albuquerque to Roswell?
Answer by CharlesG2(834) About Me  (Show Source):
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Sheri drove southeast from Albuquerque to Roswell and then south to Carlsbad. She averaged 75 mph along the route from Albuquerque to Roswell and averaged 70 mph from Roswell to Carlsbad. She covered the entire 220 miles in 3 hours. How long did she take to drive from Albuquerque to Roswell?
distance=rate*time
distance AR = x
distance RS = 220-x
x/75 + (220-x)/70 = 3
x/75 + 220/70 - x/70 = 210/70
x/75 + 10/70 - x/70 = 0
x/75 - x/70 = -10/70
70x/(75*70) - 75x/(75*70) = -10/70
70x-75x=(-10/70)*(75*70)
-5x=-10*75
5x=750
x=150 miles from Albuquerque to Roswell
150/75=2 hours