1. The problem statement, all variables and given/known data Compute P(X=k l X+Y=p) 2. Relevant equations 3. The attempt at a solution No idea. Kind of understand page #1. Although it seems like there's a lot of unnecessary stuff. Could have gone straight from the top to the bottom. And I don't know why/if you even have to substitute the X+Y=p for Y=k-p. Totally lost on page 2. No idea whats going on there. Says it's being split up because it's independent, but no idea where the 1/3 and 2/3 for 0 and 1 come form. Let alone the rest of page 2. :uhh: So, in short: What's exactly step 1,2,3 etc. ?