$[25$ points$]$ A structural element is formed using rolled$-$steel sections shown in the figure $($two L$33\frac{1}{4}$ in$,$ two L$64\frac{1}{2}$ in$,$ and one $0\mathrm{.}8-$in plate$)$

a$.$ Show that the centroidal axis $\stackrel{}{x}=0$ with respect to $y$ and $y^{\text{'}}$ axis, and $\frac{?}{\text{b}\text{a}\text{r}}(y)=11\mathrm{.}075$ above the $x$ axis $($ show all your work with proper units and proper significant Digits $)$

b$.$ Find the combined section $2^{nd}$ moment of area about the centroidal axisgiven in part a