Consider a region r bounded by r = 0, y = 0, z = 0,z+y+ z = 1. let fek. the boundary of the region r consists of 4 faces. they are in z 0,y 0,: = 0 and r+y+z = 1. show that the flux of f across the face in z = 0, with the downward orientation. is equal to the flux of f across the face in z+ y+z = 1, with the upward orientation, by using divergence theorem.