y-intercept form is y = mx + b, where m is the slope and b is the y-intercept. We know the slope is 2, so all that's left is to find the y-intercept. To do this, for every 1 we subtract from x in (4,3), we take away 2 from y because the slope is two. We keep doing this until x is zero. The remaining y-value is the y-intercept.