Time and Work – Question 37

There are three Taps A, B and C in a tank, They can fill the tank in 10 hrs, 20 hrs and 25 hrs, respectively. At first, all of them are opened simultaneously. Then after 2 hours, tap C is closed and A and B are kept running. After the 4th hour, tap B is also close(d) The remaining work is done by Tap A alone. Final the percentage of the work done by Tap A by itself.