Successive discounts of $10 \%$,$20 \%$,and $30 \%$ are equivalent to a single discount of (in $\%$):

$A$ dealer purchased an article for $Rs. 900$ and fixes the list price in such a way that he gains $20\%$ after allowing $10\%$ discount. What is the list price (in $Rs.$)?

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 $Rs.$).

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 $Rs.$)

If a shopkeeper allows a $20 \%$ discount on his advertised price and makes a profit of $25 \%$ on his outlay,what is the advertised price (in $Rs.$) on which he gains $Rs. 6000$?

While selling a watch,a shopkeeper gives a discount of $5 \%$. If he gives a discount of $7 \%$,he earns $Rs. 15$ less as profit. The marked price of the watch is (in $Rs.$):