Nutan pays $Rs.\, 2140$ for $3$ calculator and $4$ Pen while he pay $Rs.\, 1355$ for an additional calculator and $5$ Pen. Then what he paid for Calculator only in $RS.$?

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.

A fruit-seller buys some oranges and by selling $40 \%$ of them he fealises the cost price of all the oranges. As the oranges being to grow over-ripe, he reduces the price and sells $80 \%$ of the remaining oranges at half the previous rate of profit. The rest of the oranges being rotten are thrown away. The overall percentage of profit is

A man sells two article for $Rs.\,5000$ each neither losing nor gaining in the deal. If he sold one of them at a gain of $25 \%,$ the other article is sold at a loss of.......$\%$

A shopkeeper gains $17 \%$ after allowing a discount of $10 \%$ on the marked price of an article. Find his profit percent if the article is sold at marked price allowing no discount.

cost price of $100$ books is equal to the selling price of $60$ books. The gain or loss percentage will be