Respuesta :

Answer:

x = 18

Step-by-step explanation:

Vertically opposite angles are equal.

x + x + x + 90 = 144

         3x + 90 = 144  

Subtract  90 from both sides

                 3x = 144 - 90

                 3x = 54

Divide both sides by 3

                   x = 54/3

x = 18