What is the slope of the line that contains the points (4, –1) and (–1, 4)?
slope (m) of a line that passes though two points (x1,y1) and (x2,y2) is:
m=(y2-y1)/(x2-x1) or (y1-y2)/(x1-x2)
so for your case:
m= (4-(-1))/(-1-4)=5/-5=-1
so m=-1
