The probability of you rolling a 5 would be 1/6 since the cube has 6 sides and only one of the sides has a 5.
The probability that you either roll a 5 or do not roll a 5 would be 6/6 because 1/6, the probability you WILL roll a 5, and 5/6, the probability you WON'T roll a 5 added together is 6/6.
The probability that you don't roll a 5 is 5/6 because there are 5 sides of the dice that are not 5.
Hope that helped!
