From my comprehension on your description, the line is formed by connecting to points. These points are (1,-2) and (0, 2). Is that correct? :)
We can find the slope if two points of the line are known. The formula is
[tex]Slope= \frac{( y_{2}- y_{1} )}{( x_{2}- x_{1})} [/tex]
[tex]Slope= \frac{( 2- -2 )}{( 1-0)} [/tex]
Slope = -4
I hope I got it right :)
