Suppose the average daily metabolic rate for certain types of animals can be expressed as a function of mass by requals123.7m superscript 0.5, where m is the mass of the animal (in kilograms) and r is the metabolic rate (in kcal per day). (a) if the mass of an animal is changing at a rate of dm/dt, find dr/dt. (b) determine dr/dt for a 180-kg animal that is gaining mass at a rate of 3 kg per day.