3 2/7 * 1 1/3 + 3 2/7 * 1 2/3 = 3 2/7 * ( 1 1/3 + 1 2/3 ) = 3 2/7 * 3/1 = 23/7 * 3/1 =
= 69/7 = 9 6/7
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4 3/7 * 8 4/9 - 4 3/7 * 6 4/9 = 4 3/7 * ( 8 4/9 - 6 4/9 ) = 4 3/7 * 2/1 = 31/7 * 2/1 =
= 62/7 = 8 6/7
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