A men sells two houses at the rate of $Rs.\,1.995$ Lakhs each. On one house he gains $20 \%$ and on the other he loses $20 \% .$ His gain or loss per cent in the whole transaction is

A merchant buys $4000\, kg$ of wheat, one$-$fifth of which he sells at a gain of $5$ per cent, one$-$fourth at a gain of $10 \%$, one-half at a gain of $12$ percent, and the remainder at a gain of $16$ percent. If he had sold the whole at a gain of $11$ percent, he would have made $Rs.\, 72.80$ more. What was the cost price of the crop per kg? (in $Rs.$)

The list price of an article at a showroom is $Rs.\, 2000$ and it is being sold at successive discounts of $20 \%$ and $10 \% .$ Its net selling price will be (in $Rs.$)

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

A discount of $15 \%$ on one article is the same as a discount of $20 \%$ on another article. The costs of the two articles can be (in $Rs.$)

A man bought nine pens for a rupee. How many pens should be sell for a rupee to gain $50 \% ?$