If $18: x = x: 8$,then $x$ is equal to

Two numbers are in the ratio $3: 5$. If each number is increased by $10$,the ratio becomes $5: 7$. The numbers are:

An alloy of copper and zinc is taken in the ratio $1: 2$,and another alloy of the same metals is taken in the ratio of $2: 3$. How many parts of the two alloys must be taken to obtain a new alloy consisting of copper and zinc that are in the ratio $3: 5$?

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

$A$ year ago,the cost of Maruti and Figo were in the ratio of $3:4$. The ratio of present and past year costs of Maruti and Figo are $5:4$ and $3:2$,respectively. If the sum of their present costs is $7.8$ lacs,find the cost (in lacs) of Figo a year ago.

If $4 \, \text{years}$ ago the ratio between the ages of $P$ and $Q$ was $5:6$ and the sum of their ages at present is $52 \, \text{years}$, what is the ratio of their present ages?