[tex]\displaystyle\bf\\\left \{ {{4y - 5(y - x) = 8} \atop {2(3x - y) + 7y = - 14 }} \right. \\ \displaystyle\bf\\\left \{ {{4y - 5y + 5x = 8} \atop {6x - 2y + 7y = - 14 }} \right. \\ \displaystyle\bf\\\left \{ {{5x - y = 8 \: \: | \times 5} \atop {6x + 5y = - 14 }} \right. \\ \displaystyle\bf\\ + \left \{ {{25x - 5y = 40} \atop {6x + 5y = - 14 }} \right. \\ \\ 25x + 6x = 40 - 14 \\ 31x = 26 \\ x = \frac{26}{31} \\ \\ 5 \times \frac{26}{31} - y = 8 \\ \frac{130}{31} - y = 8 \\ y = 4 \frac{6}{31} - 8 \\ y = 4 \frac{6}{31} - 7 \frac{31}{31} \\ y = - 3 \frac{25}{31} [/tex]

Ответ: ( 26/31 ; - 3 25/31 )