Answer:
y=-1/2x-1
Explanation:
the slope intercept form is y=mx+b
m=slope
b=y intercept (where the line crosses the y axis)
to find slope you do rise over run or rise/run
the rise of you slope is -1, and the run of your slope is 2, meaning your slope is -1/2
the line crosses the y axis at point -1
plug what you find into the slope intercept form, and you get y=-1/2x-1