Respuesta :

1/2 (6x-4)-(3-x)=ax+x+b
3x - 2 - 3 + x = (a+1)x + b
4x - 5 = (a+1)x +b

compare constants:
b = -5

compare coefficients of x:
a +1 = 4
a = 4-1
a = 3

so, a-b = 3 - (-5) = 8