$(15$ poirits$)$ A W$25058$ rolled$-$steel over$-$hanging beam supports two loads $P$ as shown in figure below. Knowing that $P=200kN,a=50cm,$ and ${}_{\text{a}\text{l}\text{l}}=250$MPa, determine $($a$)$ the maximum value of the normial stress ${}_m$ in the beam, $($b$)$ the maximum value of the principal stress ${}_{\text{m}\text{a}\text{x}}$ at the junction of the flange and web, $($c$)$ whether the specified shape is acceptable as far as these two stresses are concerned