If A is 90% of B, then what percent of A is B?

∵ A = 90% of B
⇒ A = (90 x B)/100
Let C% of A = B
Then, (C x A)/100 = B
⇒ [C x {(90 x B)/100}] / 100 = B
∴ C = (100 x 100) / 90 =111.1