№ 1.
2/17 + 7/17 = 9/17
7/16 - 5/16 = 2/16 = 1/8 - сократили на 2
2/25 + 9/25 = 11/25
12/13 - 3/13 = 9/13
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№ 2.
1 - 2/5 = 5/5 - 2/5 = 3/5
1 - 3/4 = 4/4 - 3/4 = 1/4
1 - 4/7 = 7/7 - 4/7 = 3/7
1 - 10/11 = 11/11 - 10/11 = 1/11
№ 1.
2/17 + 7/17 = 9/17
7/16 - 5/16 = 2/16 = 1/8 - сократили на 2
2/25 + 9/25 = 11/25
12/13 - 3/13 = 9/13
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
№ 2.
1 - 2/5 = 5/5 - 2/5 = 3/5
1 - 3/4 = 4/4 - 3/4 = 1/4
1 - 4/7 = 7/7 - 4/7 = 3/7
1 - 10/11 = 11/11 - 10/11 = 1/11