Still not understanding the way to write the equation of the pair of points. (-2,-3) and (-6,-9) in the form of y=

the slope of a line is constant. The slope of the line segment between the two points is

m = ∆y/∆x = (-9+3)/(-6+2) = 3/2

Now we have the slope, and it remains constant everywhere on the line. In particular, the line segment between (-2,-3) and (x,y) is 3/2, regardless of where (x,y) is on the line.

(y+3)/(x+2) = 3/2
y+2 = 3/2 (x+2)

Review the two-point form of the line equation.