A structural I$-$ section is formed by connecting $150mm30mm$ steel plates and $120mm30mm$

steel plates along with $100mm30mm$ steel plate as shown in the diagram. For the combined section

calculate:

$($a$)$ The location $"c"$ of the principal $x-$axis $($relative to the top edge of the section$).$

$($b$)$ The second moments of area lox and Jyabout the principal $x-$ and $Y-$axes.

$($c$)$ The section moduli Zxx and Zyx for point $"A"($located at the extreme top corner of the section

$($d$)$ Calculate the moment of resistance of the combined section for bending about the $x-x$ axis,

assuming the allowable bending stress, both in tension and compression, is $200$MPa.M