Answer:

Step-by-step explanation:
On a single roll of a pair of dice. When a pair of dice are rolled the possible outcomes are as follows:
(1,1)         (1,2)          (1,3)  (1,4)  (1,5)  (1,6)
(2,1)  (2,2)  (2,3)  (2,4)  (2,5)  (2,6)
(3,1)  (3,2)  (3,3)  (3,4)  (3,5)  (3,6)
(4,1)  (4,2)  (4,3)  (4,4)  (4,5)  (4,6)
(5,1)  (5,2)  (5,3)  (5,4)  (5,5)  (5,6)
(6,1)  (6,2)  (6,3)  (6,4)  (6,5)  (6,6) 
The number of outcomes that gives us 12 are (6,6). There is only one outcome that gives us sum 12.
Total outcomes = 36
Odd against favor = 
Number of outcomes of getting sum 12 is 1
Number of outcomes of not getting sum 12 is 36-1= 35
odds against rolling a sum of 12= 