I come up with the integral from z= 1/2 to 1, integral of y=0 to sqrt(1-z2), integral from x = 0 to sqrt(1-z2-y2) of (x2+y3 - z) dxdydz.
1st integration in x gives (1-z2-y2)3/2/3 + y3(1-z2-y2)1/2 - z(1-z2-y2)1/2
Due to time constraints, I have to stop here.
If it was x2+y2 switching to cylindrical coordinates would make this easy. Even as is, switching to cylindrical makes sense.