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Looking at the figure we can see that we have 2 rectangles - refer to attached
Let us call the first A1 and the second A2.
A₁ = b₁ · h₁
A₁ = 8 · 4
A₁ = 32
A₂ = b₂ · h₂
A₂ = 8 · 4
A₂ = 32
At = A₁ + A₂
At = 32 + 32
AT = 64 a.u.
a.u. = area unit