Two numbers are such that the ratio between them is 4 : 7. If each is increase by 4, the ratio become 3 : 5. The larger number is = ?

Answer: Option C

A : B
4x : 7x
Now 4 is added to each number
$$\begin{array}{rl}& \frac{4x+4}{7x+4}=\frac{3}{5}\\ & \Rightarrow 20x+20=21x+12\\ & \Rightarrow x=8\end{array}$$
∴ Smaller number is 4 × 8 = 32
Larger number is 7 × 8 = 56