Answer
The sheet with surface charge density $\sigma$ is on one end, and the sheet with surface charge density $3\sigma$ is on the other end. The sheet with surface charge density $2\sigma$ is in the middle.
Work Step by Step
The electric field due to the sheet with surface charge density $\sigma$ is $\frac{\sigma}{2\epsilon_0}$
The electric field due to the sheet with surface charge density $2\sigma$ is $\frac{2\sigma}{2\epsilon_0} = \frac{\sigma}{\epsilon_0}$
The electric field due to the sheet with surface charge density $3\sigma$ is $\frac{3\sigma}{2\epsilon_0}$
A net electric field of $E = 0$ can be produced if the sheets with surface charge density $\sigma$ and $2\sigma$ are adjacent, and the sheet with surface charge density $3\sigma$ is on one end. Then the region between the sheet with surface charge density $2\sigma$ and the sheet with surface charge density $3\sigma$ has a net electric field of $E = 0$
A net electric field of $E = \frac{2\sigma}{\epsilon_0}$ can be produced if the sheets with surface charge density $3\sigma$ and $2\sigma$ are adjacent, and the sheet with surface charge density $\sigma$ is on one end. Then the region between the sheet with surface charge density $2\sigma$ and the sheet with surface charge density $\sigma$ has a net electric field of $E = \frac{2\sigma}{\epsilon_0}$
Therefore, the sheet with surface charge density $\sigma$ is on one end, and the sheet with surface charge density $3\sigma$ is on the other end. The sheet with surface charge density $2\sigma$ is in the middle.
