1. The problem statement, all variables and given/known data The box-like Gaussian surface of the figure below encloses a net charge of +57.0ε0 C and lies in an electric field given by = [(10.3 + 2.4x)·i - 3.1·j + bz·k ] N/C, with x and z in meters and b a constant. The bottom face is in the xz plane; the top face is in the horizontal plane passing through y2 = 3.5 m. For x1 = 2.5 m, x2 = 4.7 m, z1 = 2.2 m, and z2 = 3.9 m, what is b? Sorry that I have no figure here, hopefully you can imagine what the box looks like on the xyz plane. 2. Relevant equations I'm not sure!!! 3. The attempt at a solution I'd like to show one, but this whole thing has me stumped!! I have no clue what they mean by 10.3+2.4x i or bz k, and I don't know how to use Gauss' Law for this. I'm sorry that this is all I have, but maybe if someone could get me started by explaining the E value first! And then which form(?) of Gauss' Law to use....(Will I be integrating or not??) Thanks in advance for any and all help.