To start, the equation has to be converted to slope-intercept form, or . Start by subtracting x from both sides; , . Switch 4 and -x around to conform to the formula; . Then divide by 2 to isolate y; . This is the final equation. Because the slope of a line perpendicular is always the opposite reciprocal (i.e. The opposite reciprocal of 4 is , the opposite reciprocal of is 5) the opposite reciprocal of is 2. So the equation of the line is , and the answer is A.