Raman sells a machine for $Rs.\, 39$ lakh at a loss. Had he sold it for $Rs.\, 49$ lakh, his gain would nhave been three times the loss. What is the cost price of the machine? (in $Rs........lakh$)

A sells an article to $B$ at a gain of $20 \%$ and $B$ sells it to $C$ at a gain of $10 \%$ and $C$ sells it to $D$ at a gain of $12 \frac{1}{2} \% .$ If $D$ pays $Rs.\, 29.70,$ then $A$ purchased the article for (in $Rs.$)

The labelled price of a cupboard is $Rs$ $6500 .$ The shopkeeper sold it by giving $5 \%$ discount on the labelled price and earned a profit of $15 \% .$ What approximately is the cost price of the cupboard? (in $Rs.$)

Charging $30 \%$ above its production cost a radio maker puts a label of $Rs.\, 286$ on a ratio as its price. But at the time of selling it, he allows $10 \%$ discount on the labeled price. What will his gain be? (in $Rs.$)

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

A man buys $10$ oranges for a rupee and sells $8$ oranges for a rupee. What is the profit percent?