Respuesta :

Answer:

15

Step-by-step explanation:

Isolate the b by subtracting 6 from both sides

Question: b + 6 = 21
Subtract 6 from both sides

b + 6 - 6 = 21 - 6

b = 15

Answer:b=15

Step-by-step explanation:

Just subtract 6 from 21 to get b.