$A$ reduction of $21\%$ in the price of an item enables a person to buy $3\, Kg$ more for $₹ 100$. The reduced price of the item per $Kg$ is (in $₹$):

Oil equal to $20 \%$ of the weight of groundnut is extracted in a mill. The matter left after extraction is sold as cattle feed at the rate of $Rs. 12.5$ per $kg$. The groundnuts are bought at $Rs. 20$ per $kg$ and the processing cost is $Rs. 5$ per $kg$. At what price ($Rs.$ per $kg$) should the oil be sold to earn $20 \%$ profit on total costs (Total cost $=$ cost of groundnuts and processing costs)?

On selling an article for $Rs. 500$,the loss incurred is $20 \%$. To make a profit of $20 \%$,the article must be sold at what price in $Rs.$?

$A$ person incurs a $5 \%$ loss by selling a watch for $Rs. 1140$. At what price should the watch be sold to earn a $5 \%$ profit?

Kritika bought $25$ $i-pads$ and $i-phones$ for $Rs. 205000$. She sold $80\%$ of the $i-pads$ and $12$ $i-phones$ for a profit of $Rs. 40000$. Each $i-pad$ was marked up by $20\%$ over cost and each $i-phone$ was sold at a profit of $Rs. 2000$. The remaining $i-pads$ and $3$ $i-phones$ could not be sold. What is Kritika's overall profit/loss?

By selling an article at $\frac{2}{5}$ of the marked price,there is a loss of $25 \%$. The ratio of the marked price and the cost price of the article is