Answer:
y = 2x + 3
Step-by-step explanation:
As we go from (9,7) to (13,5), x increases by 4 and y decreases by 2. Thus, the slope of line p is m = rise/run = -2/4, or m = -1/2.
A line perpendicular to p will have a slope that is the negative reciprocal of the slope of p: -1 / {-1/2}, or m = 2.
One example of such a perpendicular line is y = 2x + 3. Here I borrowed the slope m and invented the y-intercept, b.