Question

{ x + y = 3 2 x + 3 y = 8

Answer 1

$\left \{ {{x+y=3} \atop {2x+3y=8}} \right. \\\\\\x+y=3\to x=-y+3\\\\\\ 2x+3y=8\to 2*(-y+3)+3y=8\to -2y+6+3y=8\to \\\\ -2y+3y=8-6\to y=2\\\\\\ x=-y+3\to x=-2+3\to x=1\\\\\\ S= \left \{1;2 \left \}$