A house was sold for Rs. y by giving a discount of x% , then the list price was = ?

$$\eqalign{ & {\text{Discount}} = x\% \cr & \Rightarrow {\text{Selling price}} = {\text{Rs}}{\text{.}}y \cr & \Rightarrow {\text{MRP}} = ? \cr & \Rightarrow {\text{MRP}} \times \left( {100 - x} \right)\% = y \cr & \Rightarrow {\text{MRP}} = \frac{y}{{\left( {100 - x} \right) \times \frac{1}{{100}}}} \cr & \Rightarrow {\text{MRP}} = {\text{Rs}}.\frac{{100y}}{{\left( {100 - x} \right)}} \cr} $$