Respuesta :

Step-by-step explanation:

we know that sum of all angles of a triangle is 180°

so, angle N + angle O + angle M = 180°

=> (-5b+16)+(-b+8)+(-9b-9) = 180°

=> -5b+16-b+8-9b-9 = 180°

=> -15b+15 = 180°

=> -15b = 180-15

=> -15b = 165

=> b = -165/15

=> b = -11

angle N => -5(-11)+16

=> 55+16 => 71

angle O => -(-11)+8

=> 11+8 => 19

angle M => -9(-11)-9

=> 99-9

=> 90

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