Alright! So to solve these questions, you need to find out the difference. You can use ratios to solve this. For example, question #25:
A class had 30 pupils at the beginning of this school term, but now has 5 more pupils. What is the percent of increase?
The question is basically asking how much 5 is in ratio to 30. So just divide 5 (the given amount) by 30 (the total amount). The answer is 0.16, or 16%