Ramesh marks his goods 30% above cost price. If he sells the item for Rs. 910 afters allowing of 15% discount. Find his cost price ?

\[\begin{gathered} \begin{array}{*{20}{c}} {{\text{Cost Price}}}&{{\text{Selling Price}}}&{{\text{Mark Price}}} \\ {{{10}_{ \times 20}}}&{}&{{{13}_{ \times 20}}} \\ {}&{{{17}_{ \times 13}}}&{{{20}_{ \times 13}}} \end{array} \hfill \\ \overline {\underline {{\text{ 200 unit}}\,\,\,\,\,\,\,\,\,\,\,\,\,{\text{221 unit}}\,\,\,\,\,\,\,\,\,\,\,\,{\text{260 unit}}} } \hfill \\ \end{gathered} \]

$$\eqalign{ & 221{\text{ unit }} \to {\text{ 910}} \cr & {\text{260 unit }} \to \frac{{910}}{{221}} \times 200 \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = {\text{Rs 823}}{\text{.50}} \cr} $$