O P Malhotra, S K Gupta and, Anubhuti Gangal Solutions for Chapter: Ratio and Proportion, Exercise 4: Challenge !

The ratio of the amount of water in bottle $A$ to bottle $B$ is $4 : 7$. If $\frac{1}{4}$ of the water in $A$ is poured into $B$ and then $\frac{1}{4}$ of the water in $B$ is poured into $A$, What will the new ratio be?

What should be added to each of the numbers $39, 42, 9$ $\mathrm{and} 10$ to get the numbers which are in proportion?