The marked price of a piano was $Rs. 15,000$. At the time of sale,there were successive discounts of $20\%$,$10\%$,and $10\%$ on it. The sale price was (in $Rs.$)

$A$ shopkeeper gives $12 \%$ additional discount on the discounted price,after giving an initial discount of $20 \%$ on the labelled price of a radio. If the final selling price of the radio is $Rs \, 704$,then what is its labelled price? (in $Rs$)

Kunal bought a suitcase with $15 \%$ discount on the labelled price. He sold the suitcase for $Rs. 2880$ with $20 \%$ profit on the labelled price. At what price did he buy the suitcase? (in $Rs.$)

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 $\%$.

Mahesh purchased $25\, kg$ of rice at $Rs. 32$ per $kg$ and $15\, kg$ of rice at $Rs. 36$ per $kg.$ He mixed the two varieties of rice and sold it at $Rs. 40.20$ per $kg.$ What is the percent profit earned (in $\%$)?

Paras Health Care made $3000$ strips of vitamin tablets at a cost of $Rs. 4800$. The company gave away $1000$ strips of tablets to doctors as free samples. $A$ discount of $25\%$ is given on the printed price. Find the ratio of profit in $Rs.$ if the price is raised from $Rs. 3.25$ to $Rs. 4.25$ per strip and if at the latter price,samples to doctors were done away with.