### Theory:

We always calculate the percentage profit and loss on the cost price unless otherwise stated.
Now we will learn about the essential formula for profit and loss.

1. To determine the percentage of profit:
$$\%$$ Profit $$=$$ $\frac{\mathit{Profit}}{\mathit{Cost}\phantom{\rule{0.147em}{0ex}}\mathit{price}}×100$

2. To determine the percentage of loss:
$$\%$$ Loss $$=$$ $\frac{\mathit{Loss}}{\mathit{Cost}\phantom{\rule{0.147em}{0ex}}\mathit{price}}×100$.
3. To determine the selling price/cost price for profit:
• If the profit percentage and cost price is given, we can find out selling price(S.P) of that product using the below formula.
$S.P=\frac{\left(100+\mathit{Profit}\phantom{\rule{0.147em}{0ex}}%\right)}{100}×C.P$.
• Instead of cost price, if the selling price is given and asked to find out cost price, by slightly rearranging the formula we can determine the cost price of the product.
$C.P=\frac{100}{\left(100+\mathit{Profit}\phantom{\rule{0.147em}{0ex}}%\right)}×S.P$.

4. To Determine the selling price/cost price for loss:
• If the loss percentage and cost price is given, we can find out the selling price(S.P) of that product using the below formula.
$S.P=\frac{\left(100-\mathit{Loss}\phantom{\rule{0.147em}{0ex}}%\right)}{100}×C.P$.
• Instead of cost price, if the selling price is given and asked to find out cost price, by slightly rearranging the formula, we can determine the cost price of the product.
$C.P=\frac{100}{\left(100-\mathit{Loss}\phantom{\rule{0.147em}{0ex}}%\right)}×S.P$.