№1
а) - 4/11 - 6/11 = - 10/11
б) 5/13 - 8/13 = - 3/13
в) - 8/17 - (- 12/17) = - 8/17 + 12/17 = 4/17
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№ 2
а) - 1/4 - 3/16 = - 4/16 - 3/16 = - 7/16
б) - 1/4 - (- 2/5) = - 1/4 + 2/5 = - 5/20 + 8/20 = 3/20
в) - 5/36 - ( - 5/27) = - 5/36 + 5/27 = - 15/108 + 20/108 = 5/108
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№ 3
1/28 - 5/42 = 3/84 - 10/84 = - 7/84 = - 1/12