10. x = 180-81= 99 = 180-(99+19)= 62°
11. x = 180-115= 65 = 180-(65+41)= 74°
12. x = 180-(36+42) = 102 = 180-102 = 78°
13. a = 180-(112+33) = 35°
14. b = 180-(71+35) = 74°
15. c = 180-(43+71) = 66°
