21 - 7 x 3 =
72 - 9 x 8 =
7 - 4 x ___ = 28
3 - 3 x ___ = 9
5 - ___ x 5 = 25
6 - ____ x 10 = 60
9 - 5 x ___ = 45
2 - 10 x ___ = 20
80 - 2 x 40 =