SOLUTION: a lab is testing two high-speed trains. One train travels 40 km/h faster than the other train. While one travels 70km, the other travels 60 km. Find their speeds. Please brea

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: a lab is testing two high-speed trains. One train travels 40 km/h faster than the other train. While one travels 70km, the other travels 60 km. Find their speeds. Please brea      Log On


   

Question 105914: a lab is testing two high-speed trains. One train travels 40 km/h faster than the other train. While one travels 70km, the other travels 60 km. Find their speeds.
Please break it down.. thanks
Answer by HyperBrain(694) About Me  (Show Source):
You can put this solution on YOUR website!
speed=distance%2Ftime
distance=speed%2Atime
time=distance%2Fspeed

Let x= speed of the slower train
____x+40=speed of the faster.

It took the same time for the faster one to reach 70 km and the slower one to attain 60km.
time for the slower=60%2Fx
time for the faster=70%2F%28x%2B40%29

60%2Fx=70%2F%28x%2B40%29
By cross multiplication,
60%28x%2B40%29=70x
60x%2B2400=70x
70x=60x%2B2400
70x-60x=60x-60x%2B2400
10x=2400
x=240
x%2B40=240

Therefore, their soeeds are 200 and 240 km/hr!

Power up,
HyperBrain!