Two trains start simultaneously from opposite ends of a 175-km route and travel toward each other on parallel tracks. Train X, traveling at a constant rate, completes the 175-km trip in 4 hours. Train Y, travelling at a constant rate, completes the 175-km trip in 3 hours. How many kilometers had Train X traveled when it met Train Y?
Choose the correct option.
A) 66  B) 69  C) 72  D) 75  E) 78
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 175 km to the meeting point, then Train X travels  (3/7)*175= 
<gadget id="calculator"> (3/7)*175</gadget>
<output>75</output>
75 km. The answer is 75.
<result>D</result>
Two trains start simultaneously from opposite ends of a 175-km route and travel toward each other on parallel tracks. Train X, traveling at a constant rate, completes the 175-km trip in 4 hours. Train Y, travelling at a constant rate, completes the 175-km trip in 3 hours. How many kilometers had Train X traveled when it met Train Y?