Answer:
9.1 minutes.
Step-by-step explanation:
Let t represent time taken to fill the tank.
We have been given that a cold water faucet can fill a sink in 12 min, so the part of sink filed in 1 minute would be .
The hot-water faucet can fill it in 15 min, so the part of sink filed in 1 minute would be .
The drain can empty the sink in 25 min, so the part of drain emptied in 1 minute would be .
The part of 1 full tank filled in t minutes, when both faucets are on and the drain is open would be:
Make a common denominator:
Therefore, it will take 9.1 minutes to fill the sink.