For vector calculus. Please put detailed explanation for every step of your solution.

The average value of a function f(x, y, z) over a solid region E is defined to be: 1 average value of f over E = V ( E ) f (x, y, z) dV JE Find the average value of the function f(x, y, z) = x z + y z over the region enclosed by the parabaloid z = 1 - x2 - y and the plane z = 0