Answer:
i believe the answer would be y= -x-4
Step-by-step explanation:
a line that is perpendicular, will have and opposite reciprocal slope, so:
the slope of the line y=x-4 is 1, and the reciprocal of 1 is also 1.
now take the opposite of it, which is -1.
so the perpendicular line equation would be y=-x-4
i hope this helps :D