Mr. Shamin's salary increases every year by $10 \%$ in June. If there is no other increase or reduction in the salary and his salary in June $2011$ was $Rs$ $22,385$,what was his salary in June $2009$?

$A$ man donates $30\%$ of his wealth to charity. He gives $30\%$ and $25\%$ of the remaining wealth to his wife and son respectively. The rest he divides equally between his three daughters. One of his daughters gets $Rs$ $42$ lakh as her share. What was the man's total wealth (in $Rs$ lakhs)?

$A$ student secures $90\%$,$60\%$ and $54\%$ marks in test papers with $100$,$150$ and $200$ respectively as maximum marks. The percentage of his aggregate is:

If $60 \%$ of the students in a school are boys and the number of girls is $812$,how many boys are there in the school?

In an examination,there were $2000$ candidates,out of which $900$ candidates were boys and the rest were girls. If $32 \%$ of the boys and $38 \%$ of the girls passed,then the total percentage of failed candidates is:

$A$ student multiplied a number by $\frac{3}{5}$ instead of $\frac{5}{3}$. What is the percentage error in the calculation (in $\%$)?