The marked price of an article is twice the cost price. For a gain of $30 \%$,what should be the discount percentage?

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

The true discount on a bill of $Rs. 2550$ due after $3$ months is $Rs. 50$. Find the banker's discount (in $Rs.$).

If the banker's discount on a certain sum in $2$ years at a certain rate is $Rs. 150$ and the simple interest on the same sum in $3$ years is $Rs. 240$,find the sum (in $Rs.$) and the rate of interest (in $\%$).

The banker's gain on a certain sum due in $2 \text{ years}$ at $5 \%$ per annum is $Rs. 8$. The present worth is (in $Rs.$)

The banker's gain on a bill due $1$ $year$ hence at $15 \%$ p.a. is $Rs.\, 9$. The true discount is (in $Rs.$)