How can i keep my pacman frog aquariums humidity between 75-85?

Don't listen to those people above who are telling you to waste money buying misting systems and such. What u need to do is retain humidity, not produce it. Frogs are cold blooded and you probably have a heat source to keep it warm. That heat is enough to generate the humidity. You need to focus on retaining it by closing up your tank or get a tank that holds humidity well. For high humidity creatures, the air should be stale, regardless of what other people tell you.