From a container having pure milk,$20 \%$ is replaced by water and the process is repeated thrice. At the end of the third operation,the milk is: (in $\%$ pure)

The percentage of metals in a mine of lead ore is $60 \%$. Now, the percentage of silver is $3/4 \%$ of the metals and the rest is lead. If the mass of ore extracted from this mine is $8000 \, kg$, what is the mass (in $kg$) of lead?

$A$ scored $30\%$ marks and failed by $15$ marks. $B$ scored $40\%$ marks and obtained $35$ marks more than that required to pass. The pass percentage is: (in $\%$)

If the side of a square is increased by $30 \%,$ its area is increased by:

In an election between two candidates,one got $52 \%$ of the total valid votes. $25 \%$ of the total votes were invalid. The total number of votes were $8400$. How many valid votes did the other person get?

Ram donated $4 \%$ of his income to a charity and deposited $10 \%$ of the rest in a bank. If now he has $Rs$ $8640$ left with him,then his income is