A boatman covers a distance of 24 km against water current and 36 km along the water current and takes 6 hours each time. Find the speed of water current.
A man invested \( \frac{1}{3} \) of his capital at 7%, \( \frac{1}{4} \) at 8% and the rest at 10% thereby getting an annual income of Rs.561. What was his capital?