Question

0,6*(4х-12)-0,4*(5х-7) при х=6 1/4
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Answer 1

$0.6(4x - 12) - 0.4(5x - 7) = \\ = 2.4x - 7.2 - 2x + 2.8 = \\ = 0.4x - 4.4 = \frac{2}{5} x - \frac{22}{5} = \\ = \lbrace x = 6 \frac{1}{4} = \frac{25}{4} \rbrace = \\ = \frac{2}{5} \times \frac{25}{4} - \frac{22}{5} = \frac{5}{2} - \frac{22}{5} = \\ = \frac{25 - 44}{10} = - \frac{19}{10} = - 1.9$