$4\mathrm{.}42$ The $612-$in$.$ timber beam has been strengthened by bolting to it the steel reinforcement shown. The modulus of elasticity for wood is $1\mathrm{.}8{10}^6$ and for steel is $29{10}^6.$ Knowing that the beam is bent about a horizontal axis by a couple of moment $M=450$kip$*$ in$.,$ determine the maximum stress in $($a$)$ the wood, $($b$)$ the steel.

Fig. P$4\mathrm{.}42$