Hi,
Note: the slope of the line will be 
(1-1) (3,9)
m = 9 -(-1)/ 3-1 = 10/2 = 5
m = 5 OR 5/1
the standard slope-intercept form for an equation of a line y = mx + b
where m is the slope and b the y-intercept.
y = 5x + b using ordered pair Pt(1,-1) to solve fo b
-1 = 5 + b
-6 = b
y = 5x -6 Pt(0,-6) and Pt(6/5,0) on the line
Note as y increases/decreases by 5, x increases/decreases by 1
