Simple quiz app with adsense and subscription

I want to build a quiz app which will have the following buttons on the first page : "Start general test" (it will start a test with 30 random questions from entire database..with live correct/incorrect answers and show of correct answer), another button "learning module" (which will have all the questions from DB in order..and keep track of it), a history button to see taken tests..and a static page which will open a list of categories. When clicking on a category it will show a static text from which users may learn from. I want it to include adsense and show ads of 30 sec after each 10 questions. If users want to use the full potential of the app they'll have to pay an amount as subscription. Don't post offers over 50$. I won't give more than 50.