Respuesta :

Baslel

Answer:

b

Step-by-step explanation:

If 12a + 3b = 1 and 7b – 2a = 9, what is the average (arithmetic mean) of a and b ? Add 12a+3b= 1 and 7b-2a=9, then we will get 10a+10b=10 which results 10(a+b)=10. Thus a+b=1. Therefore, the answer is B