Algebra, easy problem
posted by Larry .
Find the value of k so that the line containing the points (−4,1) and (k,−2) is perpendicular to the line containing the points (−9,5) and (−5,0).

slope of given line: 5/4
slope of ┴ line: 4/5
(21)/(k+4) = 4/5
solve for k