If the compound interest on a certain sum of money for $2 \text{ years}$ at $4 \%$ per annum is $Rs. 45.90$,the true discount on the same amount of money due $2 \text{ years}$ hence at $4 \%$ per annum simple interest is (in $Rs.$):

The selling price of an article is $Rs.\, 816$ if the discount on it is $15 \%$. What would be the selling price of the article $($ in $Rs.\,)$ if the discount on it is $25 \%$?

$A$ has to pay $Rs. 220$ to $B$ after $1$ year. $B$ asks $A$ to pay $Rs. 110$ in cash and defers the payment of the remaining $Rs. 110$ for $2$ years. $A$ agrees to it. Counting the rate of interest at $10\%$ per annum in this new mode of payment,which of the following is true?

$A$ dealer marks a washing machine for $Rs.\, 7500$ and allows a discount of $6 \%$ on it. Find its selling price in $Rs.$

Ramesh marks his goods $30 \%$ above cost price. If he sells the item for $Rs. 910$ after allowing a discount of $15 \%$,find his cost price (in $Rs.$).

If $60 \%$ discount is offered on the marked price and selling price becomes equal to cost price,then what was the percentage mark up?