Problem $4$

For the beam and loading shown, and knowing that the grade of timber used has an allowable normal stress of $12$ MPa and allowable shear stress of $0\mathrm{.}8$ MPa $.$ Find the following:

$($a$)$ Draw the shear diagram for the beam $(4)$

$($b$)$ Draw the Moment Diagram for the beam $(4)$

$($c$)$ Find the Max Shear and Moment for the beam $(2)$

$($d$)$ Determine the $h$ value so that the allowable stresses are not exceeded. $(5)$

Please solve and help me understand