Answer:
m perpendicular = - 3
Explanation:
To start with, we need to find the slope of the given line, by solving for y in the equation
x - 3 y = 12
x = 3 y + 12
x - 12 = 3 y
divide by 3 both sides:
y = x/3 - 12/3
y = (1/3) x - 4
then, the slope of the given line is 1/3, and according to the property of perpendicular lines, a perpendicular slope will be the 'opposite of the reciprocal" of the slope of the original line. That is: the value - 3.
Then the slope of the perpendicular line is: m = - 3.