Total number of possible outcomes:
[tex]6\cdot6=36[/tex]From those 36 possible outcomes the next 10 sum of at least 9 ( a number greather than or equal to 9):
[tex]\lbrace(3,6),(4,5),(4,6),(5,4),(5,5),(5,6),(6,3),(6,4),(6,5),(6,6)\rbrace[/tex]Then, the probability of obtaining a sum of at least nine when rolling a pair of dice is:
[tex]P=\frac{10}{36}=\frac{5}{18}[/tex]