You are selecting a new dishwasher. you do about 150 loads per year. the less efficient model uses 9 gallons per load. the more efficient model uses 6 gallons per load. how many gallons of water will be saved over the course of a year

Find the difference of the amount of water used per load and then multiply that by the actual number of loads per year

there is a difference of 3 gallons per load and you do 150 loads per year. Therefore, there is a savings of 450 gallons per year.