3,1(1-3у)+у=2/5(у-14)​

Ответ:

[tex]3.1(1 - 3y) + y = \frac{2}{5} (y - 14) \\ 3.1 - 9.3y + y = \frac{2}{5} y - \frac{28}{5} \\ \frac{31}{10} - 8.3y = \frac{2}{5} y - \frac{28}{5} \\ \frac{31}{10} - \frac{83}{10} y = \frac{2}{5} y - \frac{28}{5} \\ 31 - 83y = 4y - 56 \\ - 83y - 4y = - 56 - 31 \\ - 87y = - 87 \\ y = 1[/tex]