Introduction: Profit, Loss and Discount

Cost price (C.P.): This is the price at which an article is purchased.
Selling price (S.P.): This is the price at which an article is sold.

Profit or Gain: If the selling price is more than the cost price, the difference between them is the profit incurred.

Formula: Profit or Gain = S.P. – C.P.

Loss: If the selling price is less than the cost price, the difference between them is the loss incurred.
Formula: Loss = Cost price (C.P.) – Selling Price (S.P.)
Profit or Loss is always calculated on the cost price.

Marked price: This is the price marked as the selling price on an article, also known as the listed price.
Discount or Rebate: This is the reduction in price offered on the marked or listed price.

Below is the list of some basic formulas used in solving questions on profit and loss:
Gain % = (Gain / CP) * 100
Loss % = (Loss / CP) * 100
SP = [(100 + Gain%) / 100] * CP
SP = [(100 – Loss %) / 100]*CP

The above two formulas can be stated as,
If an article is sold at a gain of 10%, then SP = 110% of CP.
If an article is sold at a loss of 10%, then SP = 90% of CP.

CP = [100 / (100 + Gain%)] * SP
CP = [100 / (100 – Loss%)] * SP