The marked price of a microwave oven is ₹15,990 and it is sold for ₹12,792. What is the rate of discount offered?

​Marked price (M.P.) = ₹15,990

Selling price (S.P.) = ₹12,792

The formula for calculating the rate of discount is:

​$$\text{Discount Percentage} = \left( \frac{\text{Marked Price} - \text{Selling Price}}{\text{Marked Price}} \right) \times 100$$ 

Putting the given values in formula;

​$$\begin{aligned}&\text{Discount \%} = \left( \frac{15990 - 12792}{15990}\right) \times 100 \\ &\text{Discount \%} = \left( \frac{3198}{15990}\right) \times 100 \\ & \text{Discount \%} = 20 \% \end{aligned}$$​​