When a plot is sold for Rs. 18,700, the owner incurs a loss of 15%. This means that Rs. 18,700 represents 85% of the cost price (CP) of the plot. To find the cost price:

85% of CP=18,700 ⟹ CP=18,700×10085=22,00085%\text{ of CP}=18,700\implies CP=\frac{18,700\times 100}{85}=22,00085% of CP=18,700⟹CP=8518,700×100​=22,000

Now, to gain 15%, the selling price (SP) must be 115% of the cost price:

SP=115% of 22,000=115100×22,000=25,300SP=115%\text{ of }22,000=\frac{115}{100}\times 22,000=25,300SP=115% of 22,000=100115​×22,000=25,300

Therefore, the plot must be sold for Rs. 25,300 to gain 15%