Slopes of parallel and perpendicular lines

Question

Line a passes through points (6, 8) and (4, 1). Line b is perpendicular to a. What is the slope of line b?

Simplify your answer and write it as a proper fraction, improper fraction, or integer.

Answer 1

(6,8) (4,1)

line a has slope (8-1)/(6-4) = 7/2

a perpendicular line has the negative inverse as its slope: -2/7

just take the slope 7/2, change its sign and flip the fraction upside down