Answer: -3/4
Explanation:
You are going to change 12x - 9y = 27 to y=mx+b form because that makes it so much easier.
12x - 9y = 27
-12x -12x
-9y = -12x + 27
/-9 /-9 /-9
y = 4/3x - 3
The slope of a line that it perpendicular to another line will be the opposite reciprocal. The reciprocal of 4/3 is 3/4 and we will just change the sign of that. Your final answer will be -3/4.