Answer:
81 books
Step-by-step explanation:
Every 4 months, Eva reads 36 books.
You first need to find the number of books Eva can read in 1 month
[tex]\frac{36}{4} / \frac{4}{4} = \frac{9}{1} \\[/tex]
By dividing the ratio [tex]\frac{36}{4}[/tex] by [tex]\frac{4}{4}[/tex] you find that Eva can read 9 books per month.
You then add 4 and 5 together to get 9 because Eva has already read for 4 months and is going to read another 5 months after joining the book club.
You use the monthly ratio [tex]\frac{9}{1}[/tex] and multiply it by [tex]\frac{9}{9}[/tex] for the grand total of 81 books for the nine months that Eva has read.
