4x − 2y = 8, 2y = 4x − 8 and y = 2x − 4. In this form, we can see that the slope of the line is 2 and the y-intercept is −4 (which means the point (0,−4)). The slope of any line that is perpendicular to this one is the negative reciprocal of the slope of this line or −1/2.