If $25 \%$ of a number is subtracted from a second number,the second number reduces to its $5/6$. What is the ratio of the first number to the second number?

The total population of a village is $5000$. The number of males and females increases by $10\%$ and $15\%$ respectively,and consequently,the population of the village becomes $5600$. What was the number of males in the village?

In expressing a length $81.472 \, km$ as nearly as possible with three significant digits,find the percentage error?

In an examination,$65 \%$ of students pass in History and $55 \%$ of students pass in Hindi. If $5 \%$ of students fail in both subjects,what is the percentage of students who passed in both subjects?

If $x$ is $80 \%$ of $y$,then what percent of $2x$ is $y$?

Two jars contain equal quantities of $40 \%$ alcohol. Swati changed the concentration of the first jar to $50 \%$ by adding extra quantity of pure alcohol. Sonali changed the concentration of the second jar to $50 \%$ by replacing a certain quantity of the solution with pure alcohol. By what percentage is the quantity of alcohol added by Swati more than that replaced by Sonali?