The coordinates of a square are (-7,-7), (6,-7), (6,6) and

(-7, 6).

Step-by-step explanation:

All sides are equal since it is a square.

The length of the side joining the first 2 points is  |-7 - 6| = 13 units and it is horizontal.

The adjacent side is vertical and also has length 13  and moves up from the last line.

So the missing coordinate has a y coordinate of  6 and an x coordinate of -7.