Two gases A and B are filled at the same pressure in separate cylinders with movable pistons of radius r_A and r_B, respectively. On supplying an…

Two gases $\displaystyle A$ and $\displaystyle B$ are filled at the same pressure in separate cylinders with movable pistons of radius $\displaystyle r_A$ and $\displaystyle r_B$, respectively. On supplying an equal amount of heat to both the systems reversibly under constant pressure, the pistons of gas $\displaystyle A$ and $\displaystyle B$ are displaced by $\displaystyle 16 c m$ and $\displaystyle 9 c m$, respectively. If the change in their internal energy is the same, then the ratio $\displaystyle r_A / r_B$ is equal to