The total time taken by a boatman to row his boat upstream and downstream distance of 56 km together is 12 hours. The difference between times taken by him to row his boat another upstream and downstream distance of 42 km is 3 hours. Find the speed of boat and stream.

A 12.5 kmph, 1.5 kmph

B 10.5 kmph, 3.5 kmph

C 9.5 kmph, 4.5 kmph D one of these