Check the picture below.
so we really have 2 equal triangles with 3 rectangles, so let's get the area of each and sum them up.
[tex]\stackrel{\textit{two equal triangles}}{2\left[ \cfrac{1}{2}(8)(6) \right]}~~+~~\stackrel{back}{(6\cdot 4)}~~ +~~\stackrel{bottom}{(8\cdot 4)}~~+~~\stackrel{top}{(10\cdot 4)}\implies 144[/tex]
