7.

1) -a = 53

a = -53

2) -y = 78

y = - 78

3) -(-x) = 4

x = 4

4) -(-x) = - 38

x = - 38

5) -(-x) = - 57

x = -57

6) -y = -36

y = 36

7) -x = - 167

x = 167

8) -(-x) = - 82

x = -82