If the selling price is doubled,the profit triples. Find the profit percent.

$A$ shopkeeper mixes $20 \, kg$ of rice which cost him $Rs. \, 5$ per $kg$ with $35 \, kg$ of rice which cost him $Rs. \, 7$ per $kg$. Then he sells the mixture at $Rs. \, 6.5$ per $kg$. Find his total profit and percent profit.

Arun marks up the computer he is selling by $20 \%$ profit and sells them at a discount of $15 \%$. Arun's net gain percent is (in $\%$)

Sita sells a calculator to Gita at a gain of $17 \%$ and Gita sells it to Anu at a loss of $25 \%$. If Anu pays $Rs. 1842.75$ for it,then what did Sita pay for it? (in $Rs.$)

When a book is sold at its Marked Price,it gives a profit of $40 \%$. What percentage of profit or loss will occur if it is sold at half the Marked Price?

$A$ trader marked his goods at $20 \%$ above the cost price. He sold half the stock at the marked price,one quarter at a discount of $20 \%$ on the marked price,and the rest at a discount of $40 \%$ on the marked price. His total gain is.......$\%$