If there are 25 questions how many do you have to get right to make an 80?

To gain a score of 80% out of 25 questions you would need to answer 20 questions correctly. You can work this out for yourself quite easily... Divide 25 by 100, this gives you 0.25 which is 1% of 25. Now just multiply by 80 to get 80% of 25, which is 20.