Answer:
2/3
Explanation:
A line perpendicular to another line has a opposite reciprocal slope.
For example, if a line has a slope of 5, then the perpendicular line will have a slope of -1/5.
First, put the formula into slope intercept form:
3x + 2y = 18
2y = -3x + 18
y = -3/2x + 9
Because this line has a slope of -3/2, the perpendicular line will have a slope of 2/3.