For the cast iron beam shown, the maximum permissible compressive stress is ${}_{\text{a}\text{l}\text{l}\text{,}}=85$MPa and the maximum

permissible tensile stress is ${}_{\text{a}\text{l}\text{l}\text{,}}=125$MPa. The section is $WT26537$ which is a standard steel shape. $a=2m,b=3m$

What is the maximum bending moment in the beam in terms of applied load P $?$