The market price of an article is $Rs.$ $100 .$ If the article is sold at a discount of $10 \%,$ then $35 \%$ profit is realised. How much loss or profit will be made if it is sold for $Rs.\, 30$ less than market price?

Oil equal to $20 \%$ of the weight of ground nut 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 ground nuts are bought at $Rs.$ $20$ per $kg.$ 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)?

When a book is sold at its Marked Price it gives a profit of $40 \% .$ What $\%$ will happen if it is sold at half the marked Price?

The list price of an article at a showroom is $Rs.\, 2000$ and it is being sold at successive discounts of $20 \%$ and $10 \% .$ Its net selling price will be (in $Rs.$)

A trader had $1200\, kg$ of rice. He sold a part of it at $5 \%$ profit and the rest at $11 \%$ profit, so that he made a total profit of $7 \%$. How much (in $kg$ ) rice did he sell at $5 \%$ profit?

If the selling price of $50$ articles is equal to the cost price of $40$ articles, then the loss or gain percent is