Answer:
8 units
Step-by-step explanation:
The number 5 is 90 degrees, acute
Given is the number of science fiction books = 48
Let the number of mystery books be = x
Let the number of biographies be = y
Ratio of the number of mystery books to the number of science fiction books is 4:3 so
=

Ratio of the number of science fiction books to the number of biographies is 4:5 so 
=

Hence there are 48 science fiction books, 64 mystery books and 60 biographies.
So total number of books are = 