First we want to find the slope.
slope = (y2 - y1) / (x2 - x1)
slope = (-8 - 1) / (3 - 0)
slope = (-9) / (3)
slope = -3
Now we want point-slope form:
y - y1 = m(x - x1)
y - 1 = -3(x - 0)
y - 1 = -3x
y = -3x + 1
.
Note: We don't have to put it in slope-intercept form (y = -3x + 1). The equation y - 1 = -3(x - 0) is just as correct as y = -3x + 1. But, since teachers like it and we're used to it, slope-intercept form is a good way to put the answer.