You have the right idea so far, but you forgot to finish it up.
Point slope form is
y - y1 = m(x - x1)
where m is the slope, and (x1,y1) is the point the line goes through. As you can see, we have infinitely many choices for (x1,y1). If you use the y intercept point (0,5), then
y - y1 = m(x - x1)
y - 5 = -1(x - 0) ..... this is one of infinitely many possible answers
OR
If you use the point (2,3), then we'd say
y - y1 = m(x - x1)
y - 3 = -1(x - 2) ..... which is another possible answer
There are infinitely many other choices, but I'm only picking the points in which your teacher has shown as big dots.
By the way, nice work on getting the correct answer for the slope-intercept form.
