If Selling Price (S.P.) is more than the Cost Price (C.P.) of article/ item then the difference between selling price and cost price is known as Profit.
Profit = Selling Price (S.P.) - Cost Price (C.P)
Formula for % Gain is as follows
% Gain
$=\frac{\mathrm{Gain}}{\mathrm{C.P.}}\times 100$
Formula can be also represented as follows
% Gain
$=\frac{\mathrm{(S.P.\; -\; C.P.)}}{\mathrm{C.P.}}\times 100$
Formula for calculating Selling Price (S.P.) when % Gain/Profit and Cost Price (C.P.) is given for article.
$\mathrm{S.P.}=\frac{(100+\mathrm{\%\; Profit})}{100}\times \mathrm{C.P.}$
Formula for calculating Cost Price (C.P.) when % Gain/Profit and Selling Price (S.P.) is given for article.
$\mathrm{C.P.}=\frac{100}{(100+\mathrm{\%\; Profit})}\times \mathrm{S.P.}$