lớp 1 ???????
17 + 21 = 38
21 - 6 = 15
1 + 1 = 2
183324
17 + 21 = 38
21 - 6 = 15
??????????
1 + 1 = 2
1 + 1 + 3 + 3 + 2 + 2 = 12