Solution: The speed of old freight train is 0.5 miles per minute and the speed of new dart express train is 1.5 miles per minute.
Explanation:
Let the speed of old freight train is x miles per minute and the speed of new dart express train is y miles per minute.
It is given that the speed of the dart express train is three times faster than the freight train. So, it can be written as,
....(1)
The trains are moving towards the opposite directions, therefore the distance between them is increased at the speed of miles per minute.
The distance between both train in 15 minutes is represented by .
According to the given information the distance between trains is 30 miles in 15 minutes.
Use equation (1) and put
Put this value in equation (1), to find the value of y.
Therefore, the The speed of old freight train is 0.5 miles per minute and the speed of new dart express train is 1.5 miles per minute.
