Find the midpoint.
(x1 + x2)/2, (y1 + y2)/2
x1 = -8
x2 = 4
y1 = 1
y2 = 5
(-8 + 4)/2 = -4/2 = -2
(1 + 5)/2 = 6/2 = 3
The midpoint is (-2,3)
Does this lie on y = - x + 1
y = -(-2) + 1
y = 3 which it does
The midpoint does lie on y = - x + 1 True statement.