Question

Five books on Lisa's reading list are fiction. If this is 20% of her entire reading list, how many books does Lisa have in all?

Answer 1

Lisa would have 25 books in all

Answer 2

So if Lisa's reading list is 20% fiction, that's 20/100. So how can you simplify 20/100 so that the top number (the numerator) is 5? 
If you divide both numbers by 4 (the same as dividing the fraction by 4), then you get 5/25. That means 5 out of 25 books are fiction. Her reading list is 25 books long.