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

Find the present worth $(P.W.)$ and the true discount $(T.D.)$ reckoning $6 \%$ per annum simple interest of $Rs. 176$ due in $20 \text{ months}$ time. (in $Rs.$)

If $21 \%$ of an electricity bill is discounted,$Rs. 1817$ is still to be paid. How much was the original bill amount? (in $Rs.$)

At what percent above the cost price must a person mark the price of an article so that he can enjoy $20 \%$ profit after allowing $20 \%$ discount?

Successive discounts of $20 \%$ and $10 \%$ are given on an item marked at $Rs. 700$. Find the selling price (in $Rs.$).

$A$ owes $B$ $Rs. 1350$ due in $3$ months and $B$ owes $A$ $Rs. 1078$ due in $5$ months. If they agree to settle their account right now at $5\%$ $p.a.$ simple interest,how much should $A$ pay to $B$ (in $Rs.$)?