A shopkeeper sold two bicycles for $Rs.\,1500$ each. On one, he gains $25 \%$ and on the other he loses $20 \%$. His gain or loss per cent in the whole transaction is

Sonal buys mangoes at the rate of $3 \,kgs$ for $Rs$. $21$ and sells them at $5$ $kgs$ for $Rs.$ $50 .$ To earn a profit of $Rs.\,102,$ he must sell how many mangoes in $kgs$?

A product when sold with $10 \%$ rebate on the listed price gave a profit of $Rs$ $70 .$ What was its cost price? (in $Rs$)

The marked price of a watch was $Rs.\, 720 .$ A man bought the same for $Rs.\, 550.80$ after getting two successive discounts, the first being $10 \% .$ What was the second discount rate? (in $\%$)

On an order of $5$ dozen boxes of a consumer product, a retailer receives an extra dozen free. This is equivalent to allowing him a discount of........$\%$

A man bought orange at the rate of $8$ for $Rs.\,34$ and sold them at the rate of $12$ for $Rs.\,57.$ How many oranges should be sold to earn a net profit of $Rs.\,45?$