A merchant buys an article for Rs. 27 and sells it at a profit of 10 percent of the selling price. The selling price of the article is -

$$\eqalign{ & {\text{Let the S}}{\text{.P}}{\text{. be Rs}}{\text{. }}x. \cr & {\text{Then,}} \cr & = x - 10\% {\text{ of }}x = 27 \cr & \Leftrightarrow 90\% {\text{ of }}x = 27 \cr & \Leftrightarrow x = \left( {27 \times \frac{{10}}{9}} \right) \cr & \,\,\,\,\,\,\,\,\,\,\,\, = 30 \cr} $$