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

The ratio of incomes of $P$ and $Q$ is $3:4$ and the ratio of their expenditures is $2:3$. If at the end of the year,each saves ₹ $2000$,then the income of $P$ is (in ₹):

The ratio of the present age of Manoj to that of Wasim is $3:11$. Wasim is $12 \text{ yr}$ younger than Rehana. Rehana's age after $7 \text{ yr}$ will be $85 \text{ yr}$. What is the present age (in $\text{yr}$) of Manoj's father,who is $25 \text{ yr}$ older than Manoj?

Find the fraction which bears the same ratio to $\frac{1}{27}$ that $\frac{3}{7}$ does to $\frac{5}{9}$.

If $0.6$ times one number is equal to $0.025$ times the other,what is the ratio of the two numbers (in $/24$)?

The annual incomes and expenditures of a man and his wife are in the ratios of $5: 3$ and $3: 1$,respectively. If they decide to save equally and find a balance of ₹ $4000$ at the end of the year (total savings),their incomes were: