Respuesta :

11) x+61 +  x+51 + 80 = 180 ( angle sum property )

2x + 192 = 180

2x = 180 - 192

2x = -12

x = -12/2

x = -6

12) x+52 + 67+x + 75 = 180 ( angle sum property )

2x + 194 = 180

2x = 180 - 194

2x = -14

x = -14/2

x = -7

HOPE IT HELPS !!!

11. -6
12. -7
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