A train travelled from point A to point B at 160 Km/h. On its way back the train travelled at 120 Km/h and therefore the trip back lasted one hour longer. What is the distance (in Km) between A and B?  Pick one.
A) 480 . B) 500 . C) 510 . D) 600 . E) 800 .

Rationale: distance = speed * time d 1 = s 1 t 1 d 2 = s 2 t 2 the distance from point a to point b is the same for each trip so , d 1 = d 2 and t 2 = t 1 + 1 thus , s 1 t 1 = s 2 ( t 1 + 1 ) 160 t 1 = 120 ( t 1 + 1 ) t 1 = 3 160 * 3 = 480 answer : a
Answer: A