$A$ person purchases $8$ pens for ₹ $10$ and sells $10$ pens for ₹ $8$. How much profit or loss percentage does he make?

If the cost of $1$ banana is $Rs. 1.25$ and the cost of $1$ apple is $Rs. 1.75$,what will be the total cost of $2$ dozen bananas and $3$ dozen apples in $Rs.$?

$A$ sells an article to $B$ at a gain of $20 \%$,$B$ 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 $₹ 29.70$,then $A$ purchased the article for (in $₹$):

$A$ sells a bicycle to $B$ at a profit of $20 \%.$ $B$ sells it to $C$ at a profit of $25 \%.$ If $C$ pays $Rs. 225$ for it,the cost price of the bicycle for $A$ is (in $Rs.$)

$A$ shopkeeper sold an article offering a discount of $5 \%$ and earned a profit of $23.5 \%$. What would have been the percentage of profit earned if no discount had been offered?

$10 \%$ discount and then $20 \%$ discount in succession is equivalent to a total discount of $... \%$.