Answer:
20
Step-by-step explanation:
Number of paperback books = 4
Percentage of total books that were paperbacks = 20%
Let total number of books = x
Hence,
20% of total books = paperback books
20% of x = 4
0.2 * x = 4
0.2x = 4
0.2x / 0.2 = 4 / 0.2
x = 20
Total number of books = 20
