SOLUTION: Over a distance of 120 km , the average speed of a train 40 kmh faster than the speed of a car the train covers the distance in 30 minutes las me , in the speed of The train?

Question 1153876: Over a distance of 120 km , the average speed of a train 40 kmh faster than the speed of a car the train covers the distance in 30 minutes las me , in the speed of The train?
Found 2 solutions by josgarithmetic, mananth:
Answer by josgarithmetic(39617) (Show Source): You can put this solution on YOUR website!
What? Rewrite so it can be understood.

"the train covers the distance in 30 minutes las me , in the speed of The train?"
WHAT?
Answer by mananth(16946) (Show Source): You can put this solution on YOUR website!
let speed of train be x kmh
speed of car will be x-40 kmh
t= d/s
Time taken by car - time taken by train = 1/2
120/(x-40) -120/x = 1/2 hour
Find LCD and simplify

120x -120x+(120)(40) = (1/2)x(x-40)
4800 = (1/2)(x^2-40x)
9600 = x^2-40x
x^2-40x-9600 =0
x^2-120x+80x-9600=0

(x-120)(x+80)=0

x= 120 kmph
Speed of train 120 kmph
Speed of car = 80 kmph

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