Answer:
1. Pairs A(2, 5), B(6, 5), and C(6, 1)
missing coordinate is (2,1)
2. Pairs A(2, 3), B(7, 3), and C(7, -2)
missing coordinate is (2,-2)
3. Pairs A(-5, -1), B(1, -1), and C(1, -5)
missing coordinate is (-5,-5)
4. Pairs A(-1, 4), B(7, 4), and C(7, -1)
missing coordinate is (-1,-1)
Hope this is correct!! Have a nice day!!<3