Respuesta :

Answer:

18

Step-by-step explanation:

90 % 5 = 18 so A would measure 90º

X = 11.75

5x + 3x -4 + 90 =180
8x + 86 =180
8x = 94
X= 11.75

5x = 5(11.75) = 58.75

3x - 4 = 3(11.75) -4
35.25 -4 = 31.25

58.75 + 31.25 + 90 = 180
90 + 90 = 180
180 = 180