A18,000 - gallon pool is being filled at a rate of 20 gallons per minute. at this rate ,how many minutes will it take to fill this pool 2/5 full ? pl me

The total capacity of the pool = 18000 gallon
The total volume of the pool when calculated to 2/5 = (2/5) * 18000
                                                                                   = 35000/5 gallons
                                                                                   = 7200 gallons.
Now it is given in the problem that that
Rate at which the pool is filled with water = 20 gallons per minutes
Then
20 gallons of water is filled in = 1 minute
So
7200 gallons of water will be filled in = 7200/20 minute
                                                           = 720/2 minute
                                                           = 360 minute
So 360 minute is required to fill the pool with 2/5 of the total volume of water.