A 12 gallon tub has a faucet that lets water in at a rate of 3 gallons per minute, and has a drain that lets water out at a rate of 1.5 gallons per minute. If you start with 3 gallons of water in the tub, how long will it take to fill the tub completely?

Correct Answer: 6 minutes
Hints: tub টি ভরতে আরো পানি লাগবে (12 - 3) gallons = 9 gallons 1 মিনিটে পূর্ণ হয় ( 3 - 1.5) gallons = 1.5 gallos 1.5 gallons পূর্ণ হয় 1 মিনিটে 9 gallons পূর্ণ হয় 9/1.5 মিনিটে = 6 মিনিটে