Bob has a pair of standard dice; one die is blue, and the other die is yellow. He rolls both of his dice. How many ways could the number on the blue die be larger than the number on the yellow die?
There are a total of $6^2$ or 36, different outcomes when you roll two die.
If the blue die is x and the yellow die is y, their outcome will be (x,y)
We set x > y, so we have:
(6,1) ; (6,2) ; (6,3) ; (6,4) ; (6,5) ; (5,4) ; (5,3) ; (5,2) ; (5,1) ; (4,3) ; (4,2) ; (4,1) ; (3,2) ; (3,1); and (2,1).
15 out of the 36 outcomes work.
The answer you are looking for is 15.