The formula for point slope is written as y - y1 = m(x -x1)
You are given y - 2 = ?
Since the 2 form the point (5,2) is the y1 value, then the 5 is equal to x1
The formula becomes: y-2 = m(x-5)
Now solve for the slope, which is the change in y over the change in x:
Slope = -10 - 2 / -1 - 5 = -12/-4 = 3
Now replace m to get y-2 = 3(x-5)