A train leaves station A at 60 km/h. Two hours later, another train leaves A at 80 km/h. How long (in hours) until the second train overtakes the first?
Correct: C
Let t = time for faster train. Distance equal: 80t = 60(t + 2) → 80t = 60t + 120 → 20t = 120 → t = 6 h.