Respuesta :

damonforrest

Answer:

x=9

Step-by-step explanation:

21x-9=180

21x=189

189/21

9

Answer:

x = 9

Step-by-step explanation:

The sum of the 3 angles in a triangle = 180°

Sum the 3 angles and equate to 180

13x + 2 + 5x - 7 + 3x - 4 = 180 , that is

21x - 9 = 180 ( add 9 to both sides )

21x = 189 ( divide both sides by 21 )

x = 9