Problem Solving

Two trains start from City \(A\) and travel towards City \(B,\) which is at a distance of \(100\) miles from City \(A,\) at the same time with an average speed of \(60\) miles per hour and \(80\) miles per hour respectively. A train starts from City \(B\) at the same time and travels towards City \(A\) at an average speed of \(70\) miles per hour. How far from city \(B\) is the slower train starting from City \(A\) when the faster train starting from City \(A\) meets the train starting from City \(B?\)

A. 30 miles
B. 40 miles
C. 50 miles
D. 60 miles
E. 70 miles

Answer: D

Source: e-GMAT