Find $CP$ when $SP = Rs. 40.60$ and $\text{gain} = 16\%$.

While selling a watch,a shopkeeper gives a discount of $15 \%$. If he gives a discount of $20 \%$,he earns $Rs. 51$ less as profit. What is the original price of the watch? (in $Rs$)

The cost price of $100$ books is equal to the selling price of $60$ books. The gain percentage or loss percentage is:

Amit buys $5$ watches for $Rs. 9450$ and later sells them for $Rs. 9700$. How much profit does Amit make per watch in $Rs.$?

The cost price of an article is $64 \%$ of the marked price. Calculate the gain percent after allowing a discount of $12 \%$.

$A$ person purchases $8$ pens for ₹ $10$ and sells $10$ pens for ₹ $8$. How much profit or loss percentage does he make?