Amit purchased $13$ chairs for $Rs. 115$ each and sold all of them for $Rs. 1220$. Find the profit or loss on the transaction.

$A$ dealer fixed the price of an article $40 \%$ above the cost of production. While selling it,he allows a discount of $20 \%$ and makes a profit of $Rs. 48$. The cost of production (in $Rs.$) of the article is:

$A$ shopkeeper sells one transistor for $Rs.\, 840$ at a gain of $20 \%$ and another for $Rs.\, 960$ at a loss of $4 \%$. His total gain or loss percent is

$A$ cab driver makes a profit of $20 \%$ on every trip when he carries $3$ passengers and the price of petrol is $Rs. 30$ a litre. Find the percentage profit for the same journey if he goes with four passengers per trip and the price of petrol reduces to $Rs. 24$ a litre? (in $\%$)
(Assume that revenue per passenger is the same in both the cases.)

Nitin bought some oranges at $Rs. 40$ a dozen and an equal number at $Rs. 30$ a dozen. He sold them at $Rs. 45$ a dozen and made a profit of $Rs. 480$. The total number of dozens of oranges he bought was:

Rajesh purchased a mobile phone and a refrigerator for $Rs. 12000$ and $Rs. 10000$ respectively. She sold the refrigerator at a loss of $12\%$ and the mobile phone at a profit of $8\%$. What is her overall loss or profit?