What is the banker's discount if the true discount on a bill of Rs. 540 is Rs. 90?

As per given question,
Face Value F = 450,
True discount = 90
As we know the formula,
Present Worth, PW = Face Value − True Discount
Present Worth, PW = F − TD = 540 − 90 = Rs. 450
Hence Simple Interest on 450 = 90 − − − − − − − − − − ( 1 )
Simple Interest on the face value = Bankers Discount
⇒ Simple Interest on 540
Hence, Simple Interest on 540 = 90/450 × 540 = Rs. 108 = Bankers Discount