$A$ shopkeeper purchased $70$ $kg$ of potatoes for $Rs. 420$ and sold the whole lot at the rate of $Rs. 6.5$ per $kg$. What will be his gain percent?

On a $Rs. 10,000$ payment order,a person has a choice between three successive discounts of $10\%, 10\%$ and $30\%$ and three successive discounts of $40\%, 5\%$ and $5\%$. By choosing the better offer,how much can he save in $Rs.$?

$A$ man sells each of his $2$ articles for $Rs. 99$. On one he gains $10 \%$ and on the other he incurs a loss of $1 \%$. What is his total gain in $\%$ in the entire transaction?

$A$ man gains $20 \%$ by selling an article for a certain price. If he sells it at double the price,what will be the percentage of profit (in $\%$)?

Raman,Manan,and Kamal are partners and invest in a business such that Raman invests $\frac{2}{5}$ of the total and Manan invests $\frac{3}{8}$ of the total. What is the ratio of profits of Raman,Manan,and Kamal respectively?

If the cost price of $20$ articles is equal to the selling price of $15$ articles,find the profit percent?