Answer:4 to 3Step-by-step explanation:First, we need to know how many nonfiction books there are and how many mystery books there areWell, there are 24 mystery books and 18 nonfiction onesTo find the ratio between them, we need to compare how much 18 is to 24To do this, let's find a common factor of 18 and 24Both 18 and 24 have a common factor of 6 6 x 3 = 186 x 4 = 24So, we know that there are 4 6's in 24 and 3 6's in 18That means the ratio of 24 to 18 is the same as 4 to 3Because 18 is 3 fourths of 24So, the ratio of mystery books to nonfiction ones is 4:3