(2 - х) / 2 + 3х / 5 = 4
5(2 - х) + 6х = 40
10 - 5х + 6х = 40
х = 40 - 10
х = 30
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3/х * ух^2/ 6 = yx / 2
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= mn / p^2 * p / 4m^2n^2 = 1 / 4mn
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= (16m^3 * n^4) / (n^4 * 16m^4) = 1 / m