SOLUTION: 4. Jon travelled 800 km by car, and then returned the same distance by train. The car averaged 20
km/hr faster than the train and took 2 hours less time. What was the speed of the
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km/hr faster than the train and took 2 hours less time. What was the speed of the
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Question 742599: 4. Jon travelled 800 km by car, and then returned the same distance by train. The car averaged 20
km/hr faster than the train and took 2 hours less time. What was the speed of the car? Answer by mananth(16946) (Show Source):
You can put this solution on YOUR website! let car speed bex
distance = 800
time by car = 800/x
speed of train =(x-20)
time by train = 800/(x-20)
time by train - time by car = 2
multiply by x(x-20)
800x-800(x-20)=x(x-20)*2
800x-800x+16000=(x^2-20x)*2
/2
8000=x^2-20x
x^2-20x-8000=0
x^2-100x+80x-8000=0
x(x-100)+80(x-100)=0
(x-100)(x+80)=0
x=100 OR -80
ignore negative
speed of car = 100 kph
