The formula for slope-intercept form is y = mx + b.
M being the slope and B being the y-intercept.
The first thing I would do is find the slope. (y2-y1/x2-x1)
The slope is -3/1 or -3.
So now the equation looks like this:
y = -3x + b
Now to find the b.
The y-intercept is the value of why when x is zero. In this case it is 2.
So your answer is y = -3x + 2.
Hope this helps!