Lats call last years inventory x.
If we had a 22% increase then, it increased by .22x, resulting in x+.22x=1.22x being the inventory after the increase.
So have the current inventory, 547912.34 = 1.22x = 1.22*last years inventory.
Divide the current amount by (1+%increase) to find last years inventory amount:
547912.34/1.22 = x = last years closing inventory