By selling $80$ ball pens for $₹ 140$,a retailer loses $30 \%$. How many ball pens should he sell for $₹ 104$ so as to make a profit of $30 \% ?$

$A$ shopkeeper purchased $245$ pieces of an article at $Rs. 30$ per piece. He spent $Rs. 980$ on transport and $Rs. 1470$ on packing the articles. He sold the articles at the rate of $Rs. 50$ per piece. What is the percent profit earned?

$A$ person sells a colour $TV$ at $10\%$ below the cost price. Had he received $Rs. 1494$ more,he would have made a profit of $12 \frac{1}{2}\%$. What was the cost price of the colour $TV$ (in $Rs.$)?

At what price should a shopkeeper mark a radio that costs him $Rs. 1200$ in order that he may offer a discount of $20 \%$ on the marked price and still make a profit of $25 \% ?$

$A$ shopkeeper marks his goods at $40 \%$ above their cost price. He is able to sell $\frac{3}{4}$ of his goods at this price,and the remaining at $40 \%$ discount. Assuming that the shopkeeper is able to sell all the goods he buys,find his overall gain or loss percentage.

$A$ shopkeeper sold an item at $10 \%$ loss after giving a discount equal to half the marked price. The cost price of the item is ......... of the marked price.