$A$ businessman allows a discount of $10 \%$ on the marked price. What percent above the cost price must he mark his goods to make a profit of $17 \% ?$

$A$ person sold a radio at a loss of $5 \%$. Had he sold it for $Rs. 210$ more,he would have gained $25 \%$. For what value should he sell it in order to gain $35 \%?$

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

$A$ man bought apples at the rate of $8$ for $Rs. 34$ and sold them at the rate of $12$ for $Rs. 57$. How many apples should be sold to earn a net profit of $Rs. 45$?

$A$ fruit seller sells mangoes at the rate of $Rs. 9$ per $kg$ and thereby loses $20\%$. At what price per $kg$ should he have sold them to make a profit of $5\%$? (in $Rs.$)

$A$ man sold two watches for $Rs. 3750$ each. On one he gained $5 \%$,and on the other,he lost $5 \%$. What was his total gain or loss percentage?