The parallel axis theorem simply says that moving your axis away from the centre of gravity always increases the moment of inertia, by an amount equal to the mass times the square of the shift distance.
Here the shift distance is \(d = 50\ cm = 0.5\ m\), and the mass is \(m = 30\ kg\). So the extra term added to the centroidal value is \(m d^2 = 30 \times 0.25 = 7.5\ kg.m^2\).
Starting from the centroidal moment of inertia of \(50\ kg.m^2\), the new moment of inertia about the shifted parallel axis is \(50 + 7.5 = 57.5\ kg.m^2\).
\[\boxed{I = 57.5\ kg.m^2}\]