SOLUTION: Average Speed, Each week you must make a 180-mile trip to pick up supplies for your business. If you were to increase your speed by 5 miles per hour the trip would take 24 minutes

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Question 670129: Average Speed, Each week you must make a 180-mile trip to pick up supplies for your business. If you were to increase your speed by 5 miles per hour the trip would take 24 minutes less than usual. Find the usual average speed.
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 

Hi,

 180-mile trip 

 If you were to increase your speedhighlight%28x%29 by 5 miles per hour the trip would take 24 minutes less than usual

 t = 180/x

t - .4 = 180/(x+5)

180/x - .4 = 180/(x+5)

180(x+5) - .5x(x+5) = 180x

      900 = .5x^2 + 2.5x

          5x^2 + 25x -9000 = 0

           x^2 + 5x - 1800 = 0

      ( x -40)(x + 45) = 0 , x = 40mph   (throwing out negative solution for unit measure