two trains start simultaneously from opposite ends of a 140 - km route and travel toward each other on parallel tracks . train x , traveling at a constant rate , completes the 140 - km trip in 4 hours . train y , travelling at a constant rate , completes the 140 - km trip in 3 hours . how many kilometers had train x traveled when it met train y ?
"if the two trains cover a total distance d , then train x travels ( 3 / 7 ) * d while train y travels ( 4 / 7 ) * d . if the trains travel 140 km to the meeting point , then train x travels ( 3 / 7 ) * 140 = 60 km . the answer is a ."
multiply(divide(140, 4), divide(140, add(divide(140, 4), divide(140, 3))))