Question 1007945
1/A+1/B=1/15
12/15=4/5
Tap B is closed, leaving A to fill the remaining 1/5th in 8 hours.
(1/5)/8=1/40; meaning tap A needs 40 hours to fill the tank alone.
1/15-1/40=1/24, meaning tap B needs 24 hours to fill the tank alone. ☺☺☺☺