Answer:
24 books.
Step-by-step explanation:
The number of books that that can be fitted into the shelf is equal to the width of the self divided by the width of each book:

A=1/3h(b1-b2). So h=3/(b1-b2)
You just put two numbers that you can multiply to get the number and when you came divide anything else in the number then you circle it and that's one of the numbers
270 degrees. This is because 3 to 3:15 is a ninth degree angle. 90 times 3 equals 270. Hope this helps you!