Two places are 108 km apart. Two boats start from both places at same time towards each other. One boat is going downstream then other one is going to upstream. After how much time will they meet each other if their speeds are 12 km/hr and 15 km/hr respectively?

04 hrs

Total distance to cover by both boats = 108 km

Relative speed = 12 + 15 = 27 km/hr

Time to meet = \(\frac{108}{27}\) = 4 hours