SOLUTION: Train A is 20 mph slower than Train B. It takes Train A 2 hours longer than Train B to make a 480- mile trip. How long does it take Train A to make the trip?

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Question 754835: Train A is 20 mph slower than Train B. It takes Train A 2 hours longer than Train B to make a 480- mile trip. How long does it take Train A to make the trip?
Answer by dkppathak(439) About Me  (Show Source):
You can put this solution on YOUR website!
let train B is x mile/h
and train A is x-20 miles /h
speed =distance/time
time =distance/speed
time taken by train A =480/x-20
time taken by train B =480/x
time taken by train A - time taken by train B =2 hours
480/x-20 -480/x =2
by LCM
480(x-x+20)/x(x-20)multiplied by 2
480x20=2x^2-40x
by taking two common both side
4800=x^2-20x
x^2-20x-4800=0 by factorization
x^2-80x+60x -4800=0
(x-80)(x-60)=0
x-80=0 or x=60=0
x=80 or x=-60 neglecting negative speed
we got x=80 miles/hours
speed of train B is 80 miles/hours
train A is 60 miles /hours
ANSWER