The list price of a book is $Rs. 100$. $A$ dealer sells three such books for $Rs. 274.50$ after allowing a discount at a certain rate. Find the rate of discount in $\%$.

Profit earned by selling an article for $Rs. 1630$ is the same as the loss incurred by selling the article for $Rs. 1320$. What is the $CP$ in $Rs$?

The price of $12$ chairs and $8$ tables is $Rs. 676$. What is the price of $21$ chairs and $14$ tables in $Rs.$?

$A$ shopkeeper buys $144$ items at $90$ paisa each. On the way,$20$ items are broken. He sells the remainder at $₹ 1.20$ each. His gain percent,correct to one place of decimal,is:

An article is marked for sale at $Rs. 504$. The shopkeeper gives a discount of $5\%$ on the marked price and still earns a profit of $20\%$. What is the cost price of the article? (in $Rs.$)

$A$ tradesman gives $4 \%$ discount on the marked price and gives $1$ book free for buying every $15$ books and thus gains $35 \%$. The marked price is increased above the cost price by (approx.) (in $\%$).