Two trains A and B started from stations P and Q respectively towards each other. Train A started at 7 p.m. at a speed of 60 km/hr and train B started at 4 a.m. (next day) at a speed of 90 km/hr. The distance between the two stations P and Q is 800 km. How far from station Q will the two trains meet?

From 7 p.m. to 4 a.m. is 9 hours; train A covers 60 × 9 = 540 km before train B starts. Remaining distance = 800 - 540 = 260 km. Closing speed = 60 + 90 = 150 km/hr. Time to meet after B starts = 260/150 = 26/15 hours. Distance covered by B = 90 × 26/15 = 156 km. Distance from Q where they meet = 156 km. Wait — but option (c) is 156 km. Distance from Q = 156. Re-check: option (d) is 504. Distance from P = 800 - 156 = 644, neither. Distance B travelled from Q = 156 km, so answer is (c) 156 km.