Answer:
slope = - 

Explanation:
The equation of a line in slope- intercept form is
y = mx + c ( m is the slope and c the y- intercept )
Given
6x - 15y = 270 ( subtract 6x from both sides )
- 15y = - 6x + 270 ( divide all terms by - 15 )
y = 
 x - 18, that is
 x - 18, that is
y = 
 x - 18 ← in slope- intercept form
 x - 18 ← in slope- intercept form
with slope m = 

Given a line with slope m then the slope of a line perpendicular to it is
 = -
 = - 
 = -
 = - 
 = -
 = - 
