I'm curious - do you have any plans for doing "quality control" as more tutors join your site? What will you do if someone joins as a tutor and is giving incorrect/misleading answers to students, and getting paid for it?
1. Anonymous student ratings, if the solutions are obviously unclear or unhelpful to the student. A history feature would need to be there so the student can go back and mark a question as unhelpful or wrong even if he realises this after a week.
2. You'd need to separate unclear or unhelpful answers from plain wrong maybe? I don't know what's the line you'd need the draw but if an answer is deemed to be false, the student would be eligible for some in-app credit that he can redeem towards his next question/subscription.
3. Random cross verification of answers? Other teachers would get to judge a random answer from another teacher and provide feedback. Students would be notified automatically if an answer is revised in this way, while also providing the correct solution. Teachers can have an infraction counter or something for the same.