The ratio of ages between $A$ and $B$ is $6: 5$ and the age of each $C$ and $D$ is $\frac{9}{10}$ times that of $B$. The age of $F$ is less than $A$ but greater than $B$. The ratio of ages between $B$ and $E$ is $2: 3$. Also,the age of $A$ is $3 \text{ years}$ less than $E$. What is the ratio of the ages of $A$ and $F$ if all the ages are integers?

If $2: x :: 5: 7$,then $x$ is equal to

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

In a mixture of petrol and kerosene,the quantity of petrol is $99 \text{ litres}$. If this same quantity of petrol were present in another mixture of petrol and kerosene where the total volume is $198 \text{ litres}$ less than the actual mixture,the concentration of petrol in the actual mixture would be $13.33 \%$ less than that of the new mixture. What is the concentration (in $\%$) of petrol in the actual mixture?

There is $1000 \, \text{litres}$ of milk in a pot. $100 \, \text{litres}$ of milk is taken out and the same amount of water is poured into it. Again, $200 \, \text{litres}$ of the mixture is taken out and the same amount of water is poured into it, and finally, $400 \, \text{litres}$ of the mixture is taken out and the same amount of water is poured into it. What is the amount of milk in the resulting mixture?

The present ages of $A$ and $B$ are in the ratio $5:6$ respectively. After seven years,this ratio becomes $6:7$. Then the present age of $A$ in years is: