a)
[tex]6 \times 9 + 3 \times 9 = \\ = 54 + 27 = \\ = 81 \\ \\ \\ 6 \times 9 + 3 \times 9 = \\ = (6 + 3) \times 9 = \\ = 9 \times 9 = 81[/tex]
B)
[tex]8 \times 6 + 7 \times 8 = \\ = 48 + 56 = \\ = 104 \\ \\ \\ 8 \times 6 + 7 \times 8 = \\ = (6 + 7) \times 8 = \\ = 13 \times 8 = 104[/tex]
