A manufacturer sells an article to a wholesale dealer at a profit of $10 \%$. The wholesale dealer sells it to a shopkeeper at $20 \%$ profit. The shopkeeper sells it to a customer for $Rs.\, 56,100$ at a loss of $15 \%$. Then the cost price of the article to the manufacturer is (in $Rs.$)

If the cost price of $21$ watches is equal to the selling price of $18$ pieces, then what would be the gain percent in this transaction?

A trader buys good at $20 \%$ discount on marked price. If he wants to make a profit of $25 \%$ after allowing a discount of $20 \%$, by what percent should his marked price be greater than the original marked price?

A man buys $100\, kg$ of sugar for $Rs.\, 2400 .$ He sold $1 / 4$ th of the stock at a loss of $5 \% .$ At what per cent profit should he sell the remaining stock so as to make an overall profit of $20 \%$ on the whole transaction? (in $\%$)

A shopkeeper mixes $26\, kg$ of wheat which cost $Rs$. $20$ a $kg$ with $30\, kg$ of wheat which cost $Rs.\,36$ a $kg$ and sells the mixture at $Rs.\,30$ a $kg.$ Find the profit percent.