$A$ man bought nine pens for a rupee. How many pens should he sell for a rupee to gain $50 \%$?

By selling $80$ ball pens for $₹ 140$,a retailer loses $30 \%$. How many ball pens should he sell for $₹ 104$ so as to make a profit of $30 \% ?$

By selling an umbrella for $Rs. 300$,a shopkeeper gains $20 \%$. During a clearance sale,the shopkeeper allows a discount of $10 \%$ on the marked price. His gain per cent during the sale is

Ramesh purchased a bicycle for $Rs. 5200$ and spent $Rs. 800$ on its repairs. He had to sell it for $Rs. 5500$. Find out his profit or loss percent.

$A$ shopkeeper sells notebooks at the rate of $Rs. 457$ each and earns a commission of $4\%$. He also sells pencil boxes at the rate of $Rs. 80$ each and earns a commission of $20\%$. How much total commission will he earn in two weeks if he sells $10$ notebooks and $6$ pencil boxes a day?

$A$ shopkeeper purchased a chair marked at $₹ 600$ at two successive discounts of $15 \%$ and $20 \%$. He spent $₹ 28$ on transportation and sold the chair for $₹ 545$. His gain percent was: (in $\%$)