Find a fourth proportional to the numbers $60, 48, 30$.

If $x: y = 2: 1,$ then $(x^{2} - y^{2}) : (x^{2} + y^{2})$ is

At present,Anil is $1.5$ times Purvi's age. $8$ years hence,the respective ratio between Anil and Purvi's ages will be $25:18$. What is Purvi's present age (in years)?

If $A: B = 3: 4$ and $B: C = 8: 9$,then find the value of $A: B: C$.

If $a-b : b-c : c-d = 1 : 2 : 3$,then what is the value of $(a+d) : c$?

The ratio of the earnings of $A$ and $B$ is $4 : 7$. If the earnings of $A$ increase by $50\%$ and those of $B$ decrease by $25\%$,the new ratio of their earnings becomes $8 : 7$. What are $A$'s earnings?