9, ___, 7
12 ___ 21
91 ___ 19
3 + 4 = ___
4 + 3 = ___
6 + 6 = ___
2 + ___ = 8
8 − ___ = 2
___ − 8 = 5 5 + 8 = ___
___ − 5 = 8 8 + 5 = ___
61 + 8 = ___
43 − 4 = ___