Respuesta :

Answer:

x = 15

Step-by-step explanation:

the opposite angles of a cyclic quadrilateral sum to 180° , then

6x + 20 + 3x + 25 = 180 , that is

9x + 45 = 180 ( subtract 45 from both sides )

9x = 135 ( divide both sides by 9 )

x = 15