Question

2) {2х+15=у−12,4х + 5у = 23.

Answer 1

$\displaystyle\bf\\\left \{ {{ \frac{2x + 1}{5} = \frac{y - 1}{2} } \atop {4x + 5y = 23 }} \right. \\ \displaystyle\bf\\\left \{ {{2(2x + 1) = 5(y - 1)} \atop {4x + 5y = 23 }} \right. \\ \displaystyle\bf\\ + \left \{ {{4x - 5y = - 5 - 2} \atop {4x + 5y = 23 }} \right. \\ \\4x + 4x = 23 - 7 \\ 8x = 16 \\ x =1 6 \div 8 \\ x = 2 \\ \\ 4 \times 2 + 5y = 23 \\ 8 + 5y = 23 \\ 5y = 23 - 8 \\ 5y = 15 \\ y = 15 \div 5 \\ y = 3$

Ответ: ( 2 ; 3 )