a – 12 = 67 – 27
a = – 27 + 67 + 12
a = 52
77 – c = 55 – 22
– c = – 22 + 55 – 77
-c = -44
c = 44
9 + c = 55 – 22
c = – 22 + 55 – 9
c = 24
a – 12 = 67 – 27
a = – 27 + 67 + 12
a = 52
77 – c = 55 – 22
– c = – 22 + 55 – 77
-c = -44
c = 44
9 + c = 55 – 22
c = – 22 + 55 – 9
c = 24