If two successive discounts of $20 \%$ and $30 \%$ are given,what is the net discount (in $\%$) ?

The true discount on a certain bill due for nine months at $4 \%$ simple interest is $Rs.\, 150$. Find the amount of the bill (in $Rs.$).

$A$ man bought a motorcycle for $Rs. 32500$. He sold it for $Rs. 35000$,allowing the buyer a $6$ months credit. If the money is worth $4\%$ per annum,the gain percent is (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 $Rs.$).

If the selling price is $Rs. 1680$ after getting a discount of $16 \%$ what was the marked price? (in $Rs.$)

The true discount on a bill of $Rs. 720$ is $Rs. 80$. The banker's discount is (in $Rs.$)