Question 523656
YOur aunt and uncle have been visiting at your home. 

Five minutes after they drive away, you realize that they forgot thier bags.
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You happen to know that they drive slowly, so you get in your car and drive to catch up to them.
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Your average speed is 10 mph faster than their average speed,and you catch up with them in 25 minutes. 
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How fast did you drive?
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"Your" DATA:
rate = r+10 mph ; time = 25 min = 5/12 hr ; distance = r*t = (5/12)(r+10) miles
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"Their" DATA:
rate = r mph ; time = 30 min = 1/2 hr ; distance = r*t = (1/2)r miles
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Equation:
your distance = their distance
(5/12)(r+10) = (1/2)r
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Multiply thru by 12 to get:
5(r+10) = 6r
5r+50 = 6r
r = 50
r = 10 mph (Their driving rate)
r+10 = 20 mph (Your driving rate)
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Cheers,
Stan H.
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