Dice roll probability, get 9 total

If I roll two dice, what is the probability the sum of the amounts is nine?

Answer: The probability is 1/9

 
Explanation:
The sum of 9 can be rolled in 4 ways:
A={(3,6),(4,5),(5,4),(6,3)}
The total number of possible results is: S =  6*6=36

Cell containing a number 9 in red is our chances to get total sum 9

The probability is:
P(A) = A / S = 4 / 36 = 1 / 9

source: stackexchange