Respuesta :

Answer:

q = 12    i hope this helps you!   :)

Step-by-step explanation:

you should take the 9 from both sides leaving you with the following equation

12 = q

you need to flip the equation around to have the variable on the left side of the equation

q = 12

Bring 9 to the other side of the =
21-9= 12
q=12