Question 77309
At a given hour, two cars leave a city in the same direction.  One travels at 60 mph, and the other travels at 75 mph. In how many hours will the cars be 90 miles apart?
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1st car:
rate = 60 mph ; time=x hrs.  ; distance 60x miles
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2nd car:
rate = 75 mph ; time = x hrs. ; distance = 75x miles
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EQUATION:
2nd car distance - 1st car distance = 90 miles
75x - 60x = 90
15x = 90
x=6 hrs (time after they will be 90 miles apart)
Cheers,
Stan H.