jmc

The common difference $d$ is $85-88=-3$, so the $n^{\text{th}}$ term in the arithmetic sequence is $88-3(n-1)=91-3n$. If $91-3n=-17$, then $3n=(91+17)=108$, so $n=108/3=36$. Hence, $-17$ is the $36^{\text{th}}$ term in this arithmetic sequence, which means that $36-1=\boxed{35}$ terms appear before $-17$ does.