If you roll two dice, there are 6•6 possible outcomes (36 outcomes). That’s your denominator.
To roll a 9, you’d need
Die 1: 3, Die 2: 6
Die 1: 4, Die 2: 5
Die 1: 5, Die 2: 4
Die 1: 6, Die 2: 3
There are 4 ways to roll a nine, so that’s your numerator.
4/36 or 1/9 is your probability.
