The points (x-1,y+2) and (x,y) lie on the same line. How to determine the slope of the line?

We'll recall the formula that gives the slope of the line
that passes through two
points:

m=(y2-y1)/(x2-x1)

Let
x1 = x-1, y1 = y+2 and x2 = x, y2 = y.

We'll substitute
them in the formula of the slope:

m = [y-(y+2)]/[x -
(x-1)]

We'll remove the brackets and we'll
get:

m = (y-y-2)/(x-x+1)

We'll
eliminate like terms and we'll have:

m =
-2/1

m = -2

The
required slope of the line that passes through the points (x-1,y+2) and (x,y), is m =
-2.