A beam has the cross section shown below. On a section where the resisting moment is $Mr-75kN-$m $($negative bending$),$ determine the maximum tensile flexural stress.

$90\mathrm{.}3$MPa

$100\mathrm{.}3$ MPa

$116\mathrm{.}7$ MPa

$115\mathrm{.}3$ MPa