How many pairs of natural numbers is there the difference of whose squares are 45.

Explanation:-

(x² - y²) = 45;
Or, (x - y)(x + y) = 45.
Thus, the factors of 45 possibles are 15, 3, 9, 5, 1 and 45.
Hence, numbers are 9 and 6 or 7 and 2 or 23 and 22.
So, number of such pairs = 3.