Question 847210
I apologize for last time. I made a slight error. 

P[multiple of 3] = 1/3  =  12/36
P[sum of 8] =  5/36

However as I said last time (3,5) is not the only roll that satisfies both, we also have (6,2). This means we need to take in account the 2 cases out of 36 where both events take place. 

So we calculate  12/36 + 5/36 - 2/36 =   5/12  which is our answer.