smc

The original line can be adjusted to standard form, in which it is $x-3y=7$. Because this line is in standard form, its slope is $\frac{-1}{-3}=\frac{1}{3}$. Thus, the slope of the perpendicular line is the negative reciprocal of this number, $-3$. Because we know that this new line passes through the point $(0,4)$, we can describe this line using point-slope form, in which it is $y-4=-3(x-0)$, or $y+3x-4$, which is answer choice $\boxed{y+3x-4=0}$.