The slope-intercept form:
[tex]y=mx+b[/tex]
m - slope
b - y-intercept → (0, b)
We have the points (2, 0) and (0, -2) - y-intercept → b = -2.
The formula of a slope:
[tex]m=\dfrac{y_2-y_1}{x_2-x_1}[/tex]
Substitute:
[tex]m=\dfrac{-2-0}{0-2}=\dfrac{-2}{-2}=1[/tex]