The true discount on a bill of $Rs. 720$ is $Rs. 80$. The banker's discount is (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 $21 \%$ of an electricity bill is discounted,$Rs. 1817$ is still to be paid. How much was the original bill amount? (in $Rs.$)

$A$ owes $B$ $Rs. 1350$ due in $3$ months and $B$ owes $A$ $Rs. 1078$ due in $5$ months. If they agree to settle their account right now at $5\%$ $p.a.$ simple interest,how much should $A$ pay to $B$ (in $Rs.$)?

$A$ 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?

$A$ $20 \%$ discount is offered on an item. By applying a promo code,the customer wins $30 \%$ cash back. What is the effective discount? (in $\%$)