Answer:
The 36 is the total number of choices possible. Two cubes are rolled. If a 1 is rolled on one cube, there are 6 possible choices on the other cube (1, 2, 3, 4, 5, 6). If a 2 is rolled on one cube, there are 6 possible choices on the other cube (1, 2, 3, 4, 5, 6). After doing this for all 6 numbers on the first cube, you find that there are 6+6+6+6+6+6 or 6*6 possible choices. 6*6 is 36, so that is where the 36 is from. You can also use the Fundamental Counting Principle.