Please explain; algebra class

A ham is taken out of the oven. Its internal temperature is 160 F, and placed in a room that is 79 F. The amount of time it takes for the ham to cool to a temperature of x degrees F is given by the equation f (x) = 120 . In 81 x-79 A) What is the proper domain for this function? (What temperatures make sense?) Answer using interval notation. B) Sketch a graph of the function. Make sure to have an appropriate window, scale, label all axes, and important features of the graph. C) Use the graph of the function to determine the temperature of the ham after 15 minutes. Round to the nearest tenth. D) Write the equation that needs to be solved to answer Part C). Convert this equation to exponential form, and solve for the answer algebraically