Example $4\mathrm{.}2$: Consider the beam discussed in Example $4\mathrm{.}1.$ Use a rectangular cross$-$section of width $300mm$ and overall depth of $700mm.$ For analysis purposes, use an effective depth of $650mm.$ the beam is properly reinforced. The concrete and steel material properties are given below. Find the factored moment resistance for the beam section.

Material properties:

$f_s=25$MPa

$f_y=400$MPa

${}_c=0\mathrm{.}65$

${}_s=0\mathrm{.}85$