Respuesta :

Answer:

b = 21 +8a

Step-by-step explanation:

We can dive both sides by 2 to get:

-8a + b = 21

Then bring at 8a to both sides to get

b = 21+8a

Answer:

-16a+2b=42

2b=42+16a

b=42+16a

²

b=21+8a