According do what i came up with. after 3 hours train (A) should be 150 miles out towards Smithville, while Train (B) will be 180 miles out towards Westtown. Its best to graph this out to better understand. so 330/2 = 165, so thats your half way point. use this to determine how far train (A) is from SV compared to train (B)s distance to WT. After 3 hours you can see at 180 miles out Train (B) will be crossing paths with Train (A) at 150 miles. So the answer would be 3 hours