The age of the father is $30 \text{ years}$ more than the son's age. Ten $\text{years}$ hence,the father's age will become three times the son's age at that time. What is the son's present age in $\text{years}$?

Eighteen $years$ ago,the ratio of $A$'s age to $B$'s age was $8: 13$. Their present ages are in the ratio $5: 7$. What is the present age of $A$ (in $years$)?

The average age of $11$ players of a cricket team is increased by $2$ $months$ when two of them aged $18\, years$ and $20\, years$ are replaced by two new players. The average age of the new players is:

The age of the father $10 \,years$ ago was thrice the age of his son. Ten $years$ hence,father's age will be twice that of his son. The ratio of their present age is

$7$ years ago,the ages (in years) of $A$ and $B$ were in the ratio $4:5$; and $7$ years hence they will be in the ratio $5:6$. The present age of $B$ is (in years):

The average age of women and child workers in a factory was $15 \text{ years}$. The average age of all the $16$ children was $8 \text{ years}$ and the average age of women workers was $22 \text{ years}$. If $10$ women workers were married,then the number of unmarried women workers is: