X+1620=12450-4980 y-1620=12450-4980
x=7470 x=7470
x=7470-1620 x=7470+1620
x=5850 x=9090
--------------------------------- ----------------------------
5850+1620=12450-4980 9090-1620=12450-4980
7470=7470 7470=7470
C-1620=12450+4980
x=7470
x=7470+1620
x=9090
---------------------------------
9090-1620=12450-4980
7470=7470