[tex]\displaystyle\bf\\\left \{ {{6x + 5y = 7 \: \: | \times 2 } \atop {8x - 2y = 4 \: \: | \times 5 }} \right. \\ \displaystyle\bf\\ + \left \{ {{12x + 10y = 14 } \atop {40x - 10y = 20 }} \right. \\ \\ 12x + 40x = 20 + 14 \\ 52x = 34 \\ x = \frac{34}{52} \\ x = \frac{17}{26} \\ \\ 6 \times \frac{17}{26} + 5y = 7 \\ \frac{51}{13} + 5y = 7 \\ 5y = 7 - 3 \frac{12}{13} \\ 5y = 3 \frac{1}{13} \\ y = \frac{40}{13} \div 5 \\ y = \frac{40}{13 \times 5} \\ y = \frac{8}{13} [/tex]

Ответ: ( 17/26 ; 8/13 )