$300\, gm$ of salt solution has $40 \%$ salt in it. How much salt should be added to make it $50 \%$ in the solution? (in $gm$)

Sourav purchased $30 \text{ kg}$ of rice at the rate of $₹ 10$ per $\text{kg}$ and $35 \text{ kg}$ at the rate of $₹ 11$ per $\text{kg}$. He mixed the two. At what price per $\text{kg}$ should he sell the mixture to make a $30\%$ profit in the transaction?

$A$ man has given ₹ $300000$ as a loan. He lent some of his capital to Ajay at an interest rate of $20 \%$ per annum and the rest to Ramesh at an interest rate of $12 \%$ per annum. At the end of one year,he received $17 \%$ of his total capital as interest. How much did he lend to Ajay? (in ₹)

$A$ man has $40 \ kg$ of tea,a part of which he sells at $5 \%$ loss and the rest at the cost price. In this business,he incurs a total loss of $3 \%$. Find the quantity of tea which he sells at the cost price (in $kg$).

$18 \text{ litre}$ of pure water was added to a vessel containing $80 \text{ litre}$ of pure milk. $49 \text{ litre}$ of the resultant mixture was then sold,and some more quantity of pure milk and pure water was added to the vessel in the respective ratio of $2:1$. If the resultant respective ratio of milk and water in the vessel was $4:1$,what was the quantity of pure milk added in the vessel? (in $\text{litre}$)

In what ratio must a grocer mix two varieties of pulses costing $Rs. 15$ and $Rs. 20$ per $kg$ respectively so as to get a mixture worth $Rs. 16.5$ per $kg$?