1. P = (G * N * Q) / 100,
2. Discount = List Price - Selling Price. Discount (%) = (Discount/List Price) × 100.
3. Suppose, TD = True discount, F = Face value of bill, R = rate of interest, BD = Bankers discount, PW = Present worth, and T = time (years) So, simple interest levied on the face value for the bill for unexpired time = BD = FTR/100. Therefore, PW = F/(1 + T(R/100))
