Two large metal sheets carry surface currents as depicted in the...

The magnetic field due to a large infinite metal sheet carrying a surface current density $K$ is uniform and its magnitude is given by $B = \dfrac{\mu_0 K}{2}$.

For the top sheet, the current is coming out of the plane of the paper. By the right-hand thumb rule, the magnetic field produced by it is directed towards the left above the sheet and towards the right below the sheet.

For the bottom sheet, the current is going into the plane of the paper. The magnetic field produced by it is directed towards the right above the sheet and towards the left below the sheet.

At point $P$ (above both sheets):
The field due to the top sheet is $\dfrac{\mu_0 K}{2}$ towards the left.
The field due to the bottom sheet is $\dfrac{\mu_0 K}{2}$ towards the right.
Net magnetic field at $P = 0$.

At point $Q$ (between the sheets):
The field due to the top sheet is $\dfrac{\mu_0 K}{2}$ towards the right.
The field due to the bottom sheet is $\dfrac{\mu_0 K}{2}$ towards the right.
Net magnetic field at $Q = \dfrac{\mu_0 K}{2} + \dfrac{\mu_0 K}{2} = \mu_0 K$ towards the right.

At point $R$ (below both sheets):
The field due to the top sheet is $\dfrac{\mu_0 K}{2}$ towards the right.
The field due to the bottom sheet is $\dfrac{\mu_0 K}{2}$ towards the left.
Net magnetic field at $R = 0$.