Question 867251
Two trains made the same 315-mile run. Since one train traveled 10 mph faster than the other, it arrived 2 hours earlier. Find the speed of each train.
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let x=speed of slower train
x+10=speed of faster train
travel time=distance/speed
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{{{315/x-315/(x+10)=2}}}
LCD:x(x+10)
315(x+10)-315x=2x(x+10)
315x+3150-315x=2x^2+20x
2x^2+20x-3150=0
x^2+10x-1575=0
(x+45)(x-35)=0
x=-45 (reject, x>0)
or
x=35
x+10=45
speed of slower train=35 mph
speed of faster train=45 mph