In a class of $60$ students, $40\%$ can speak only Hindi, $25\%$ can speak only English and the rest of the students can speak both the languages. How many students can speak English?

Sunil decided to donate $5 \%$ of his salary. On the day of donation,he changed his mind and donated $₹ 1687.50$,which was $75 \%$ of what he had decided earlier. How much is Sunil's salary?

The number of students in a class is increased by $20 \%$ and the number now becomes $66$. Initially,the number was:

In a recent opinion poll held during April,$60 \%$ of the respondents favoured India Against Corruption $(IAC)$ while the rest favoured Indian political parties $(IPP).$ It was found in May polls that $10 \%$ of $IAC$ supporters switched their preference to $IPP,$ while the same percentage of $IPP$'s supporters also switched their preference to $IAC.$ What percentage of the electorate should now switch their preference from $IAC$ to $IPP$ so that they are at par?

The monthly income and monthly expenditure of a person were $₹ 13500$ and $₹ 9000$ respectively. In the next year,his income increased by $14 \%$ while his expenditure increased by $7 \%$. The percentage increase in his savings is: (in $\%$)

Ravi is $12$ years younger than Surya. Ravi's age is $40 \%$ of the sum of his and Surya's age. What will be Surya's age $9$ years hence?