If the line is perpendicular, then its slope is the reciprocal of the given line's slope. This new line's slope is 1/2. We plug it into slope-intercept form
y = 1/2x + b
Now plug in the given point of (2, 10) and solve for b.
10 = 1/2(2) + b
10 = 1 + b
9 = b
So your equation is y = 1/2x + 9
