At a crime scene, police officers find a murder victim in a tub full of warm water. A thermometer shows that the water temperature is 75 degrees F and the air temperature is 70 degrees F. It is known that most people fill a tub with water at 100 degrees F. Find Newton's Law of cooling and use it to model the temperature of the water in the tub(using a heat transfer coefficient of k=0.018). To the nearest whole minute, how long has the bathtub water been cooling?