Final answer:
The slope of line b is the negative reciprocal of line a, therefore, it's -1/m. Line c will have the same slope as line a, which is m, because lines b and c are also perpendicular.
Step-by-step explanation:
The question involves understanding the concept of slope in straight lines when discussing perpendicular lines. If the slope of line a is m, to find the slopes of lines b and c we need to use the fact that perpendicular lines have slopes that are negative reciprocals of each other.
For line b to be perpendicular to line a, if line a has a slope m, line b must have a slope that is the negative reciprocal of m, meaning line b's slope is -1/m. Since line b is also perpendicular to line c, it follows that line c would have the same slope as line a, which is m.