The difference between successive discounts of $40 \%$ followed by $30 \%$ and $45 \%$ followed by $20 \%$ on the marked price of an article is $Rs.\,12.$ The marked price of the article is (in $Rs.$)

The cost price of $20$ articles is the same as the selling price of $x$ articles. If the profit is $25 \%$, then the value of $x$ is in $Rs.$

A man sells an article at $5 \%$ above its cost price. If he had bought it at $5 \%$ less than what he had paid for it and sold it at $Rs.\, 2$ less, he would have gained $10 \% .$ The cost price of the article is (in $Rs.$)

A man buys two chairs for a total cost of $900.$ By selling one for $\frac{4}{5}$ of its cost and the other for $\frac{5}{4}$ of its cost, he makes a profit of $90$ on the whole transaction. The cost of the lower priced chair is (in $Rs.$)

A trader marked his goods at $20 \%$ above the cost price. He sold half the stock at the marked price, one quarter at a discount of $20 \%$ on the marked price and the rest at a discount of $40 \%$ on the marked price. His total gain is…….$\%$