only Question C and D please$I_z=15\mathrm{.}52{10}^{6}m{m}^4$

$I_z=(\frac{b_i{d}_i^3}{12}+b_1{d}_1($ dist ${?}_{(}()i){)}^2)$

$=\frac{80{16}^3}{12}+8016(172-103\mathrm{.}07{)}^2=60928\mathrm{.}139$

$+\frac{8{152}^3}{12}+8152(88-103\mathrm{.}07{)}^2=2617364\mathrm{.}892$

$+\frac{60{12}^3}{12}+6012(6-103\mathrm{.}07{)}^2=6792901\mathrm{.}128$

:$\mathrm{.}15\mathrm{.}52{10}^{6}m{m}^{4}OK$

C$/$ Normal Stress due to axial force & moment

$=\frac{P}{A}+-\frac{M_y}{I_z}$

${}_{\text{T}\text{O}\text{P}}=\frac{20}{3216}+\frac{20{10}^6(180-103\mathrm{.}07)}{15\mathrm{.}52{10}^6}$

$=6\mathrm{.}22+99\mathrm{.}14$

${}_{\text{T}\text{O}\text{P}}=+105\mathrm{.}35$MPa