The proof is about finding the slope of AE BF and CD, so midpoints have nothing to do with it.
It's also not the definition of a slope and it also doesn't have to do with parallel lines because it mentions none of it in previous statements.
Thus the answer is using the point-slope formula as the previous statement was entirely dedicated to finding the coordinates for the points. All statement 7 did was to plug those values in to get the slope.
ik how do do this just give me a few minutes and i will give it to
∆abc has the points a(1, 7), b(-2, 2), and c(4, 2) as its vertices. formed with the point d(1, 2) as its third vertex, then ∆abd is triangle.
definition of midpoint