$1$ A cast iron beam has a section shown in figure below. The figure is symmetrical about the axis Y$-$Y$.$ Determine the position of the neutral axis of the axis $\backslash (\backslash$mathrm$\{$X$\}-\backslash$mathrm$\{$X$\}\backslash ).$ If when subjected to a bending moment in the plane Y$-$Y$,$ the tensile stress at the bottom edge is $24$ Mpa find the values of the bending moment expressing it in $\backslash (\backslash$mathrm$\{$kN$\}-\backslash$mathrm$\{$m$\}\backslash )$ and the stress at the top edge $(10$ mks $)$