A farmer measured the quantity of water in a tank 10 days after it was filled and found it to be 2000
gallons. After the next 5 days, it was measured again and found to contain 1300 gallons. Assume
that the amount of water in the tank decreases at a constant rate. Find the slope of the linear
relation between L, the number of liters of water consumed, and the number of days after the tank
was filled