A trader allows a trade discount of $20 \%$ and a cash discount of $6 \frac{1}{4} \%$ on the marked price of the goods and gets a net gain of $20 \%$ of the cost. By how much above the cost should the goods be marked for the sale? (in $\%$)

By selling an article for $Rs.\, 21,$ a man lost such that the percentage loss was equal to the cost price. The cost price of the article was (in $Rs.$)

A shopkeeper allows a discount of $10 \%$ on the marked price of an item but charges a sales tax of $8 \%$ on the discounted price. If the customer pays $Rs.\, 3,402$ as the price including the sales tax, then the marked price is (in $Rs.$)

A plate was sold for $Rs.\,6,300$ after giving two successive discounts of $12^{1 / 2} \%$ and $10 \% .$ Find the marked price. (in $Rs.$)

If $5 \%$ more is gained by selling an article for $Rs.\, 350$ than by selling it for $Rs$ $340,$ the cost of the article is......$\%$

By selling $90$ pens for $Rs.\, 80$ a man loses $20 \%$. What should be the selling price (in $Rs.$) of $90$ pens for $20\%$ profit?