The differential equation below models the temperature of an 87°C cup of coffee in a 23°C room, where it is known that the coffee cools at a rate of 1°C per minute when its temperature is 73°C. Solve the differential equation to find an expression for the temperature of the coffee at time t. (Let y be the temperature of the cup of coffee in °C, and let t be the time in minutes, with t = 0 corresponding to the time when the temperature was 87°C.)