Answer:
4
Explanation:
The slope of the line in the image is -1/4. I found that by starting at the point (0,2) and moving down 1, and right 4. This is because slope is rise over run, meaning that you move up/down and then right/left. You can see that the line is sloping downwards, so it is negative.
Perpendicular lines have a slope that is the opposite reciprocal, meaning the sign is opposite and the numerator and denominator are flipped (reciprocal). The current slope is -1/4, so the reciprocal is -4/1 (or just -4). Then just make the negative positive and you get 4.