Two trains, A and B, started simultaneously from opposite ends of a 120-mile route and traveled toward each other on parallel tracks. Train A, traveling at a constant rate, completed the 120-mile trip in 6 hours; Train B, traveling at a constant rate, completed the 120-mile trip in 4 hours. How many miles had train A traveled when it met train B? Choose the correct option
A) 28
B) 36
C) 48
D) 50
E) 54

Rationale: "as the ratio of the rates of a and b is 4 to 6 then the distance covered at the time of the meeting ( so after traveling the same time interval ) would also be in that ratio , which means that x would cover 4 / ( 4 + 6 ) = 4 / 10 of 120 miles : 120 * 4 / 10 = 48 miles . answer : c ."
Answer: C