Respuesta :

Answer:

x = 20

Step-by-step explanation:

4x + 5x = 9x

9x = 180 (supplementary angles add up to 180 degrees)

Divide 180/9 = 20

Answer:

x = 20.

Step-by-step explanation:

Supplementary angles sum to 180, so:

4x + 5x = 180

9x =  180

x = 20.