QUESTION $2$: A $1\mathrm{.}2m$ long timber box beam is simply supported at both ends and is constructed by gluing two $12mm$ thick x $450mm$ high plywood sheets to two $100mm$ x $150mm$ boards, as shown in Section A$-$A below. At the location of Section A$-$A$,$ determine the following values:

a$)$ The maximum compressive normal stress;

b$)$ The shear stress along the glue joints at the top of the beam; and

c$)$ The maximum shear stress in the plywood.