Well we are given f(n) and f(0) so lets start by plugging them in first.
You should be able to finish this and use the same methodology for number 2.
As a side note,
I just plugged in the values to the equation. We were given f(n) and f(0) so I substitute those in to the equation f(n)=n+f(0)+f(n-1).
For f(n-1), I plugged in n-1 for n in the f(n) equation. Thus, and simplify. Now, we have all pieces to our f(n) equation. From here, your goal is to make the left hand side(LHS) look like the RHS.