a bathtub contains 45 gallons of water and the total weight of the tub and water is approximately 697.275 pounds. you pull the plug and the water begins to drain. let v represent the number of gallons of water that has drained from the tub since the plug was pulled. note that water weights 8.345 pounds per gallon. write an expression in terms of v that represents the weight of the water that has drained from the tub (in