Nutan pays $Rs. 2140$ for $3$ calculators and $4$ pens,while she pays $Rs. 1355$ for $1$ additional calculator and $5$ pens. What is the cost of a calculator in $Rs.$?

$A$ shopkeeper sold one-third of his goods at a loss of $15 \%$. To get a profit of $10 \%$ on the whole transaction,he should sell the remaining articles at a profit of in $\%$?

$A$ trader buys two articles for $Rs. 4000$ each. While selling,if he gains $12.5\%$ on one and loses $20\%$ on the other,what will be the overall loss percent (in $\%$)?

$A$ cloth merchant sold half of his cloth at $20 \%$ profit,half of the remaining at $20 \%$ loss,and the rest was sold at the cost price. In the total transaction,his gain or loss will be

$A$ man sells each of his $2$ articles for $Rs. 99$. On one he gains $10 \%$ and on the other he incurs a loss of $1 \%$. What is his total gain in $\%$ in the entire transaction?

$A$ pen was sold for a certain sum and there was a loss of $20 \%$. Had it been sold for $Rs. 12$ more,there would have been a gain of $30 \%$. What would be the profit percentage if the pen was sold for $Rs. 4.80$ more than the original selling price?