Distance with variables

[mbokhari]

Came across this problem at MGMAt. Need the algebraic solution.

A high speed train covers the distance Z between A and B at x miles per hour at a constant rate. A regular train covers the same distance at y mph at a constant rate. If the high speed train leaves town A and regular train leaves town B then how much more distance will the high speed train have covered than the regular train when they meet/cross each other??

[4GMAT_Mumbai]

Hi,

Relative speed = (x+y) mph, as they are traveling in opposite directions.

Time taken for the two trains to meet = D / (x+y)

In these many hours,

distance traveled by the high speed train = Dx / (x+y)

distance traveled by the regular train = Dy / (x+y)

Difference between distances = D (x-y) / (x+y)

PS: Assumption is that both the trains started at the same time.

Hope this helps. Thanks.