Two successive discounts of $4 \%$ on any item are equivalent to a single discount of $\%$

Hundred oranges are bought at the rate of $Rs. 350$ and sold at the rate of $Rs. 48$ per dozen. The percentage of profit or loss is:

$A$ shopkeeper sold chairs at $Rs. 2139$ each after giving a $7 \%$ discount on the labelled price. Had he not given the discount, he would have earned a profit of $15 \%$ on the cost price. What was the cost price of each chair? (in $Rs.$)

$A$ trader sold an article at a gain of $20 \%$. Had he purchased it for $40 \%$ more and sold for $Rs. 24$ less,he would have incurred a loss of $20 \%$. What is the cost price (in $Rs.$) of the article?

If Aditya sells an article to Nutan at $10 \%$ gain,while Nutan sells it to Manish at $20 \%$ gain at $Rs. 1914$,then what is the Cost Price in $Rs.$?

If the cost price of $20$ articles is equal to the selling price of $15$ articles,find the profit percent?