If line b is perpendicular to line a, and line c is perpendicular to line a, what is the slope of line c ?

To answer this question, we must find the slope of line b.
 We have then:
 b = (3 - (- 2)) / (2 - (- 3))
 b = 5/5
 b = 1
 Since the lines b and c are parallel, it follows that their slopes are equal.
 Then
 mc = b = 1
 
 The slope of line c is:
 mc = 1