Two concentric imaginary spherical surface of radius R and 3R, respectively, surrounds a point charge -Q, located at the center of the surface. When compared to the electric flux I1 through the surface of radius R, the electric flux I2 through the surface 3R is. I know the answer is that I1=I2 based on Gauss's Theorem, I=q/ε, where q is the charge enclosed. But wouldn't the two flux's change if we instead use, I=E(dA), because of different radius in the dA portion? Can someone explain to me how will we get the same, I, if we use the latter equation? Thanks.