In a class there are $z$ students. Out of them $x$ are boys. What part of the class is composed of girls?

If $a:b = \frac{2}{9} : \frac{1}{3}$,$b:c = \frac{2}{7} : \frac{5}{14}$,and $d:c = \frac{7}{10} : \frac{3}{5}$,then find $a:b:c:d$.

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

The difference between the ages of Meena and Seema is $3 \ yr$ and the ratio between their ages is $7: 8$. What is the sum of their ages (in $yr$)?

Two numbers are in the ratio $3: 5$. If $9$ is subtracted from each,the new numbers are in the ratio $12: 23$. The smaller number is:

₹ $11,550$ has to be divided between $X$,$Y$,and $Z$ such that $X$ gets $\frac{4}{5}$ of what $Y$ gets and $Y$ gets $\frac{2}{3}$ of what $Z$ gets. How much more does $Z$ get over $X$ (in ₹)?