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

Seema sells a pen to Sapna at a profit of $25 \% .$ Sapna sells it to Asha at a profit of $10 \%$ and Asha sells it to Kavita at a profit of $5 \%$. If Asha sells it for $Rs.\,231,$ find the cost price at which Seema bought the pen? (in $Rs.$)

$20 \%$ loss on selling price is what per cent loss on the cost price? (in $\%$)

Half of $100$ articles were sold at a profit of $20 \%$ and the rest at a profit of $40 \% .$ If all of the articles had been sold at a profit of $25 \%,$ the total profit would have been $Rs.\,100$ less than earlier profit. The cost price of each article was (in $Rs.$)

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

Selling price of a glass is $Rs.\, 1965$ and loss per cent is $25 \%$. If selling price is $Rs.\,3013,$ then what will be the profit percent?