D + 1/5 = 4/7 + 3/7
d + 1/5 = 10/7
d = 1 3/7 - 1/5 = 1 21/35 - 7/35 = 1 14/35 = 1 2/5
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f + 4/5 = 4/7 + 3/7
f = 1 3/7 - 4/5 = 1 21/35 - 28/35 = 56/35 - 28/35 = 28/35
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b + 2/5 = 4/7 + 3/7
b = 1 21/35 - 2/5 = 1 21/35 - 14/35 = 1 7/35 = 1 1/5
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28/35 < 1 1/5 < 1 2/5
f < b < d
Ответ уравнение c переменной f