You can
put this solution on YOUR website!28x14 what? feet?
What shape is the pool? Rectangular...easy...Other shape more complicated.
Convert everything to inches or to feet and find te volume.
Once you have a volume in that unit (call it y), find out how many of these (call this x) are in 1 gallon (from your textbook) --> i am in the UK and we do not use Imperial measurements much anymore, just metric.
Once you have 1 gallon = x (whatevers)
then find 1/x gallons = 1 (whatevers)
then find (1/x)*y gallons = y whatevers.
Jon.