Answer
See the picture
Work Step by Step
Note that there are six terms in the expression, two p's, q's, and r's. Four of these are negated, so we must put inverters after these (namely, p, r, q, and p). Now we have two subexpressions $\neg p\vee\neg r$ and $q \vee r$. So we need to add two "or" gates between the corresponding terms. The next subterms we need are the $\neg q$ and $\neg p$. Now we use two "and" gates to create the $(\neg p\vee\neg r)\wedge\neg q$ and $\neg p\wedge(q\vee r)$. Finally, we add an "or" gate between these two to create the final expression.
