Let $M$ be the event of the Moon being full $90\%$ or more and $H$ be the event of the dog howling. It is given: $$P(M)=0.1,P(M')=1-P(M)=0.9;\\\ P(H|M)=0.95, P(H'|M)=1-P(H|M)=0.05;\\\ P(H|M')=0.35, P(H'|M')=1-P(H|M')=0.65;\\\ P(M|H)=?\\\$$ The Bayes' rule (conditional probability): $$ P(M|H)=\frac{P(M\cap H)}{P(H)}=\frac{P(M)\cdot P(H|M)}{P(M)\cdot P(H|M)+P(M')\cdot P(H|M')}$$ Can you finish?