5 4/9 - 4,5 = 5 4/9 - 4 1/2 = 5 8/18 - 4 9/18 = 4 26/18 - 4 9/18 = 17/18
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5 4/9 + 4,5 = 5 4/9 + 4 1/2 = 5 8/18 + 4 9/18 = 9 17/18
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5 4/9 ÷ 4,5 = 49/9 ÷ 9/2 = 49/9 × 2/9= 98/81 = 1 17/81
5 4/9 × 4,5 = 49/9 × 9/2 = 49/2 = 24,5