Question $1$: For the beam cross$-$section shown in Figure $1$:

$($i$)$ Determine the lever arm.

$($ii$)$ Determine the ultimate moment of resistance.

Use $f_{cu}=25\frac{N}{m}{m}^2$ and $f_y=500\frac{N}{m}{m}^2$

Figure $1.$ Cross section of a rectangular beam $($All dimensions are in $mm)$