Find $SP$ when $CP = Rs. 56.25$ and $\text{Gain} = 20\%$?

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

$A$ and $B$ jointly made a profit of $Rs. 1650$ and they decided to share it such that $\frac{1}{3}$ of $A$'s profit is equal to $\frac{2}{5}$ of $B$'s profit. Then the profit of $B$ is (in $Rs.$)

$A$ trader marked the selling price of an article at $10 \%$ above the cost price. At the time of selling,he allows a certain discount and suffers a loss of $1 \%$. He allowed a discount of $\%$:

In a certain store, the profit is $320 \%$ of the cost. If the cost increases by $25 \%$ but the selling price remains constant, approximately what percentage of the selling price is the profit?

Arun purchased $30 \, kg$ of wheat at the rate of $Rs. \, 11.50$ per $kg$ and $20 \, kg$ of wheat at the rate of $Rs. \, 14.25$ per $kg$. He mixed the two and sold the mixture. Approximately at what price per $kg$ should he sell the mixture to make $30 \%$ profit? (in $Rs.$)