SOLUTION: Gerald drove 120 miles to his parent's home. His return trip took 1 hour less because he drove 20 mph faster. How fast did Gerald drive going to his parents house?

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Question 853216: Gerald drove 120 miles to his parent's home. His return trip took 1 hour less because he drove 20 mph faster. How fast did Gerald drive going to his parents house?
Answer by lwsshak3(11628) About Me  (Show Source):
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Gerald drove 120 miles to his parent's home. His return trip took 1 hour less because he drove 20 mph faster. How fast did Gerald drive going to his parents house?
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let x=speed Gerald drove to his parent's home
x+20=speed of Gerald's return trip
travel time=distance/speed
..
travel time to house-travel time of return trip=1 hr
120%2Fx-120%2F%28x%2B20%29=1
LCD:x(x+20)
120(x+20)-120x=x(x+20)
120x+2400-120x=x^2+20x
x^2+20x-2400=0
(x+60)(x-40)=0
x=-60 (reject)
or
x=40
speed Gerald drove to his parent's home=40 mph