if i understand correctly what you mean by this question the answer could be
14/24
28/48
you can just keep multiplying the top and the bottom by the same number to get an equivalent fraction
im sorry if i understood the question wrong, i hope this helped a little bit
The midpoint of (x1,y1) and (x2,y2) is

just average them
(4,1) and (-2,4)
the midpoint is

(1,-1.5)