Mary rolls two, numbers of cubes with sides numbered from 1 to 6.what is the probability that one of the numbers is a 2 and the sum of the numbers facing up on both cubes us less than, orequal to 6?

Assume we have 2 cubes as described, one blue, the other red.

The Event  E: "one is a 2, and the sum is < or equal to 6" is:

E={(Red 2, Blue 1), (Red 2, Blue 2), (Red 2, Blue 3), (Red 2, Blue 4),                 (Red 1, Blue 2), (Red 2, Blue 2), (Red 3, Blue 2), (Red 4, Blue 2)}

thus, n(E)=8, 

The sample space S (the set of all the possible accounts) is:
 
{(Red x, Blue y | x ∈ 1, 2, 3, 4, 5, 6 ; y∈ 1, 2, 3, 4, 5, 6}

That is n(S)= 6*6 = 36,

as any of the 6 possibilities for x, can be combined with of the 6 possibilities for y.

P(E)=n(E)/n(S)=8/36=0.222

8/36=0.222