Hitesh is $40$ years old and Ronnie is $60$ years old. How many years ago was the ratio of their ages $3:5$?

The incomes of $A, B$ and $C$ are in the ratio $7: 9: 12$ and their expenditures are in the ratio $8: 9: 15$. If $A$ saves one-fourth of his income,then the ratio of the savings of $A, B$ and $C$ is:

The ratio of wine and water in a drum is $3:1$. What part of the mixture is taken out and replaced with an equal amount of water so that the ratio of wine and water in the mixture becomes $1:1$?

The ratio of the present ages of $R$ and $S$ is $11:17$. $11$ years ago,the ratio of their ages was $11:20$. What is $R$'s present age (in years)?

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

If $A : B = 2 : 3$,$B : C = 4 : 5$ and $C : D = 5 : 9$,then $A : D$ is equal to