Abiologist tracks the number of bacteria. when the water has no chemicals, the number of bacteria (b) is 1200 per gallon. for each tablespoons of the chemical solution (c) added to each gallon of water, the number of bacteria decreases by 75 per gallon. how much of the chemical, in the tablespoons must be added to a 500 gallon tank to reduce the bacteria count to a safe 300 bacteria per gallon?