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

$A$ bill is discounted at $5 \%$ per annum. If banker's discount be allowed, at what rate of interest must the proceeds be invested, so that nothing is lost? (in $\%$)

The price of an article is cut by $42 \%$. To restore it to its original value,the new price must be increased by (in $\%$):

When a discount of $Rs. 42$ is allowed on the marked price of an article,the new reduced price becomes $86 \%$ of the original marked price. Find the marked price (in $Rs.$).

The banker's discount on a sum of money for $1 \frac{1}{2}$ years is $Rs.\, 837$ and the true discount on the same sum for $2$ years is $Rs.\, 900$. The rate percent is:

The banker's discount on a certain sum of money is $Rs. 84$ and the true discount on the same sum for the same time is $Rs. 70$. The sum due is (in $Rs.$)