By selling a mirror for $₹1904$, Manoj made$12\%$ profit. For how much did he purchase the mirror?

Finding the cost price of the mirror

Given,

$$\begin{gathered} \mathrm{S}.\mathrm{P}=₹1904 \\ \mathrm{Profit}\mathrm{percent}=12\% \end{gathered}$$

We know that, $\mathrm{Profit}\%=\frac{\mathrm{S}.\mathrm{P}-\mathrm{C}.\mathrm{P}}{\mathrm{C}.\mathrm{P}}\times 100$

Putting the values, we get

$$\begin{gathered} \Rightarrow 12=\frac{1904-C.P}{C.P}\times 100 \\ \Rightarrow 12C.P=190400-100C.P \\ \Rightarrow 12C.P+100C.P=190400 \\ \Rightarrow 112C.P=190400 \\ \Rightarrow C.P=\frac{190400}{112} \\ \Rightarrow C.P=1700 \end{gathered}$$

Hence, cost price of the mirror is $₹1700$