Answer:
Step-by-step explanation:
Let, the number of the books will be x.
With the first method, the total cost will be, $(19521 + 21x) and with the second method, the total cost will be $(62265 + 11.25x).
As per the given condition it is told that the costing should be equal.
Hence, [tex]19521 + 21x = 62265 + 11.25x\\x = 4384[/tex].