12,449899597988873 вот такой ответ
Х=(2,5: 1 целую2/13+5/6): 3/7
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x=2 целых 5/6 ^ 3/7
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х=119/18
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если не ошибаюсь
135, 157, 179, 315, 351, 357, 375, 359, 379, 319, 513, 531, 537, 571, 539, 591, 593, 597, 713, 715, 719, 731, 735, 739, 791, 793, 795, 751, 753, 759, 913, 915, 931, 935, 917, 937, 951, 953, 957, 971, 973, 975
1) (1/6 + 2/3) * 3 = 5/6 * 3 = 5/6 * 3/1 = 5/2 = 2 1/2
2) (17/30 - 2/15) : 13 = 13/30 : 13 = 13/30 * 1/13 = 1/30
3) (1/8 + 3/4) : 5 = 7/8 : 5 = 7/8 * 1/5 = 7/40
4) (4/3 + 1/9) * 4 = 13/9 * 4 = 52/9 = 5 7/9
5) (1/2 + 1/3) * 2 = 5/6 * 2 = 5/3 = 1 2/3
6) (1/2 - 1/3) * 3 = 1/6 * 3 = 1/2