Respuesta :

retirEEd

Answer:

see below

Step-by-step explanation:

 a + b = 4

 a -  b = 8        add the two equations to solve the system of equations

a + a + b + (- b) = 4 + 8

 2a  + 0b = 12

      2a/2  = 12 /2

           a  =  6

    a + b = 4

    a - a + b = 4 -a

            b = 4 - 6

            b =  -2