+612 A line passes through the midpoint of $(1,2)$ and $(19,4)$. The line is perpendicular to a line through $(0,7)$ and $(4,-3)$. What is the $y$-coordinate of the line when $x=20$?
+129899 Midpoint of (1,2) , (19,4) = ( 10, 3)
The line containing points (0,7) and (4, - 3) has a slope of [ -3 - 7] / [4 - 0] = -10/4 = -5/2
So....a line perpendicular to this will have a slope of 2/5
So....the equation of this line is
y = (2/5)(x - 10) + 3
y = (2/5)x - 4 + 3
y = (2/5)x - 1
So....when x = 20
y = (2/5)(20) - 1
y = 8 - 1
y = 7
EDITED TO CORRECT A SIGN ERROR
