5). 18 × 1 = 18
2 × 9 = 18
3 × 6 = 18
6). a). 9 + 8 = 17
b). 9 × 8 = 72
c). 9 - 8 = 1
d). 9 × 3 = 27
7). 6 × a = 54
a = 54 : 6
a = 9
b × 8 = 56
b = 56 : 8
b = 7
8). 6 × ( 5 + 3 ) = 6 × 8 = 48
6 × 5 + 6 × 3 = 30 + 18 = 48
9 × ( 9 - 2 ) = 9 × 7 = 63
9 × 9 - 9 × 2 = 81 - 18 = 63