The perimeter is 1/2 the perimeter of ABCD because the scale factor is 1/2. It would be 10 units.
I believe the answer would be 3/40
To find the answer, you must find the midpoint of their x-coordinates and their y-coordinates. To do that, you take the average between their x and y-coordinates.
So, in this case, it is:
x: (12+12)/2 = 24/2 = 12
y: (7-3)/2 = 4/2 = 2
So, the answer is: (12,2)