A bar is fixed between two unyielding walls. The left segment is aluminium, 200 mm long, A = 900 mm^{2}, E = 70 GPa; the right segment is steel, 300 mm long, A = 1200 mm^{2}, E = 200 GPa. An axial load P = 200 kN acts at the junction B, directed towards the steel segment. Find the stress (MPa) in each material.