# A calculus problem by Hobart Pao

Calculus Level pending

Find the volume under the surface bounded by the planes $$z=x+1, z=-x+1, z=y+1, z=-y+1$$ and above the $$xy$$ plane. If the answer can be represented in the form $$\dfrac{a}{b}$$, where $$a, b$$ are coprime positive integers, find $$a + b$$.

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