If $33 \%$ of $A$ is equal to $55 \%$ of $B$,then find the ratio of $A$ and $B$.

Find the mean proportional between $9$ and $64$.

The present ages of three persons are in the ratio $4: 7: 9$. Eight years ago,the sum of their ages was $56$. Find their present ages (in $years$).

The ratio of the number of boys and girls in a school is $8: 12$. If $50 \%$ of boys and $25 \%$ of girls are getting scholarships for their studies,what is the percentage of school students who are not getting any scholarships (in $\%$)?

The sum of three numbers is $124$. If the ratio between the first and second is $2:3$ and that between the second and third is $7:9$,then the third number is

Find the number which,when subtracted from the terms of the ratio $12: 17$,makes it equal to the ratio $2: 3$.