Suppose the average daily metabolic rate for certain types of animals can be expressed as a function of mass by r= 145.3m , where m is the mass of the animal (in kilograms) and r is the metabolic rate (in kcal per day). dm dr a. If the mass of an animal is changing at a rate of dt -, find dt dr b. Determine dt for a 90-kg animal that is gaining mass at a rate of 2 kg per day. . . . dm dr a. If the mass of an animal is changing at a rate of dt find dt dr at