The pressure diagram is triangular in nature for both, assuming you don't have a surcharge on the wall. Of course the real question here, then, is what is the slope of the line for each of the soils. For that I will ask you to refer to the text book you've been given in class. Most if not all practicing civil/structural engineers can immediately recognize the earth pressure diagram as well as determine the pressure values.
If you would like for our members to explain the problem in more detail, discuss this with your professor and have him indicate as much to us.
