When a discount of $20 \%$ is given on a sweater,the profit is $28 \% .$ If the discount is $14 \%,$ then the profit is (in $\%$)

$A$ bill for $Rs. 8000$ is drawn on September $19$ for $6$ months. It is discounted on January $8$ at $10\%$. Find the banker's discount,true discount,banker's gain,and the money that the holder of the bill receives (in $Rs.$).

$A$ watch dealer pays $10 \%$ customs duty on a watch which costs $Rs.\, 500$ abroad. He desires to make a profit of $20 \%$ after giving a discount of $25 \%$ to the buyer. The marked price should be (in $Rs.$)

If $Rs. 21$ is the true discount on $Rs. 371$ for a certain time,what is the true discount on the same amount for double that time,the rate being the same in both the cases? (in $Rs.$)

At $20 \%$ discount,the selling price of an article is $Rs. 2400$. What is the selling price (in $Rs.$) if the discount is $32.5 \%$?

The true discount on a bill of $Rs. 5450$ due in $9$ months is $Rs. 450$. Find the rate of interest (in $\%$).