Properties of Solids and Liquids: JEE Main 2026 Physics question

A metal string $A$ is suspended from a rigid support and its free end is attached to a block of mass $M$. Second block having mass $2M$ is suspended at the bottom of the first block using a string $B$. The area of cross sections of strings $A$ and $B$ are same. The ratio of lengths of strings of $A$ to $B$ is 2 and the ratio of their Young's moduli ($Y_A/Y_B$) is 0.5. The ratio of elongations in $A$ to $B$ is ______.