5. En cada uno de los pasos escribe la propiedad que se emplea

) (a + b) + (c + d) = [ (a + b) + c] + d__________________________
= [ c + (a + b)]+ d __________________________
= [(c + a) + b] + d__________________________
= (c + a) + (b + d)_________________________
b) 4[(x + y) + z] = 4[z + (x + y)]__________________________
= 4z + 4(x + y)__________________________
= 4z + 4x + 4y__________________________
= 4z + (4x + 4y)__________________________
= (4x + 4y) + 4z__________________________