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

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 $Rs. 6000$?

The true discount on a bill of $Rs. 5450$ due in $9$ months is $Rs. 450$. Find the rate of interest (in $\%$).

An article is sold for $Rs. 6552$ after a discount of $22 \%$. What is the marked price (in $Rs.$) of the article?

The true discount on a bill of $Rs.\, 1260$ due for $6$ months at $10 \%$ per annum is (in $Rs.$):

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