Find a simple discount equivalent to a discount series of $10 \%, 20 \%$ and $25 \%$ (in $\%$).

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

After selling $5 \%$ of a quantity of sugar,$5 \text{ kg}$ of sugar remains. Find the total quantity of sugar in $\text{kg}$.

Raman sells a machine for $Rs. 39$ lakh at a loss. Had he sold it for $Rs. 49$ lakh,his gain would have been three times the loss. What is the cost price of the machine? (in $Rs. \text{ lakh}$)

When a book is sold at its Marked Price,it gives a profit of $40 \%$. What percentage of profit or loss will occur if it is sold at half the Marked Price?

$A$ pair of articles was bought for $Rs. 37.40$ at a discount of $15 \%$. What must be the marked price of each of the articles?