A = (5, 2)
r: y = 2 - 1/4 x
s ⊥ r Rightarrow s : y = a + 4x
A in s Rightarrow 2 = a + 4 * 5 Rightarrow a = -18
s cap r = M: 2 - 1/4 x = -18 + 4x // this is cohordinate x of M
8 - x = -72 + 16x Rightarrow 80 = 17x
M = (80/17, 2 - 20/17) = (A + B)/2 // middle point of A and B
80/17 = (5 + x)/2 and 14/17 = (2 + y)/2 // cohordinates of B
160 = 85 + 17x and 28 = 34 + 17y
75 = 17x and -6 = 17y