find the midpoint of the line segment joining (4/5,-2/3) and (-8/5,-6).

The midpoint between two points (x1, y1) and (x2, y2) is given by

M=((x1+x2)/2, (y1+y2)/2)

Here  (x1, y1) =(4/5,-2/3) and (x2, y2) = (-8/5,-6).  Therefore

M=((4/5-8/5)/2, (-2/3-6)/2) = (-2/5, -10/3)