(7 + 3) + 2 = 2 + (7 + 3)
3(2x + 4) = 6x + 12
(9. x)3 = 9. (x · 3)
(8.x. 2) = (8.2.x)
(4 + 5) + 1 = 4 + (5 + 1)
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