The price of a washing machine, inclusive of Tax, is ₹ 13,530/-. If the tax is 10%, find its basic (cost) price.

Given:

Selling price of the washing machine = ₹ 13,530

and, Tax = 10% of marked price

Let the marked price be ₹ $x$.

$x + \text{10\% of x} = ₹ 13,530\\[1em] \Rightarrow x + \dfrac{10}{100} \times x = ₹ 13,530\\[1em] \Rightarrow x + \dfrac{1}{10} \times x = ₹ 13,530\\[1em] \Rightarrow \dfrac{10x}{10} + \dfrac{x}{10} = ₹ 13,530\\[1em] \Rightarrow \dfrac{(10x + x)}{10} = ₹ 13,530\\[1em] \Rightarrow \dfrac{11x}{10} = ₹ 13,530\\[1em] \Rightarrow x = ₹ \dfrac{13,530 \times 10}{11}\\[1em] \Rightarrow x = ₹ \dfrac{1,35,300}{11}\\[1em] \Rightarrow x = ₹ 12,300\\[1em]$

Hence, the cost of washing machine is ₹ 12,300.