  We propose a universal formula of dc electrical conductivity in rotational-
and translational- symmetries breaking systems via the holographic duality.
This formula states that the ratio of the determinant of the dc electrical
conductivities along any spatial directions to the black hole area density in
zero-charge limit has a universal value. As explicit illustrations, we give
several examples elucidating the validation of this formula: We construct an
anisotropic black brane solution, which yields linear in temperature for the
in-plane resistivity and insulating behavior for the out-of-plane resistivity;
We also construct a spatially isotropic black brane solution that both the
linear-T and quadratic-T contributions to the resistivity can be realized.
