15-x=8,15+c=26,79-x=46+9,45+y=100-15,45+y=100-15,13-a=21-12,12+c=90-70.
X=8-15. c=26-15. x=46+9-79. x=-7. c=11. X=-24 y=100-15-45. -a=21-12-13. y=40. a=5 C=90-70-12 C=8