From the question, Elsa pumped 18 gallons of water out of her pool and this was done over a period of 3 minutes at a constant rate. Since it is done at a content rate, to get the change in the amount of water in the pool each minute, we divide 18 gallons by 3. This can be written mathematically as:
= 18 gallons ÷ 3
= 6 gallons
Change = -6
The change in the amount of water in the pool each minute will be -6gallons
