let the mid point cordinate be (x,y)

and we are given A(0,3) And M (-3,7)

so we will find by using x={0+(-3)}/2=-3/2

y={3+7}/2=10/2=5

Hence, the cordiantes are (x,y) is (3/2,5)

question no.2—The angles are having 2 pairs of vertically opposite angles.

If you draw a cross then label the angles ,you will find that 1&3 ,2&4 are facing each other.

the property applied here is that these two pairs are vertically opposite angles.they are equal to one another,hence 1=3 and 2=4

so,(6y +29)=(12y -7)

6y-12y=-7-29

-6y=-36

y=6

similarly,(4x+31)=(6x – 11 )

4x-6x=-11-31

-2x=-42

x=21