Question

{5(x-3y)-6=2x+1
{3(x+6y)+4=9y+19
​

Answer 1

$\left \{ {{5(x-3y)-6=2x+1} \atop {3(x+6y)+4=9y+19}} \right. \\\\\left \{ {{5x-15y-6=2x+1} \atop {3x+18y+4=9y+19}} \right.\\\\\left \{ {{3x-15y=7} \atop {3x+9y=15}} \right.\\\\$

Решаем подстановки:

$\left \{ {{3x=7+15y} \atop {7+15y+9y=15}} \right.\\\\$

$\left \{ {{3x=7+15y} \atop {24y=8}} \right.\\\\$

$\left \{ {{3x=7+15\cdot \frac{1}{3} } \atop {y=\frac{1}{3} }} \right.\\\\$

$\left \{ {{3x=7+5 } \atop {y=\frac{1}{3} }} \right.\\\\$

$\left \{ {{x=4 } \atop {y=\frac{1}{3} }} \right.\\\\$

О т в е т.   $(4;\frac{1}{3})$