When rolling two dice. possible outcomes are:

(1,1)(1,2).....(1,6)

(2,1)(2,2).....(2,6)

..

..

(6,1)(6,2)....(6,6)

Then the total possible outcomes is 36

Now, possible outcomes for a totatl of 8 is:

(2,6)(6,2)(3,5)(5,3)(4,4) = 5

Then probability is= 5/36