Respostas

2013-09-23T18:29:31-03:00
30-{4+[(6:2)+4-2]}=
30-{4+[(3)+2]}=
30-{4+[3+2]}=
30-{4+[5]}=
30-{4+5}=
30-{9}=
30-9=
21
2013-09-23T21:13:24-03:00
30 - { 4 + [ 3 + 2 ] } =
30 - { 4 + 5 } =
30 - 9 = 21