When an article is sold for ₹$474$, there is a loss of $21\%$. The cost price of the article (in ₹) is:

Let the cost price ($CP$) of the article be $100\%$.Selling at a loss of $21\%$ implies that the selling price is $100\%-21\%=79\%$ of the $CP$.
$$79\%\text{ of }CP=474$$
$$\frac{79}{100}\times CP=474$$
$$CP=\frac{474\times 100}{79}$$
Simplifying the calculation ($79\times 6=474$):
$$CP=6\times 100=\text{₹}600$$