Draw the SFD and BMD and determine the maximum bending stress: 20 kN at the free end A, supports at B (2.5 m from A) and D; 40 kN at C (3 m from B); CD = 2 m; rectangular section 80 mm wide × 250 mm deep. Give R_{B} (kN), the maximum bending moment (kN·m, magnitude) and σ_{max} (MPa).