Question

x - y = 10
2x + 3y = 10

Answer 1

$\left \{ {{x-y=10} \atop {2x+3y=10}} \right.$

$\left \{ {{3x-3y=30} \atop {2x+3y=10}} \right.$

$(3x-3y)+(2x+3y)=30+10$

$3x-3y+2x+3y=40$

$5x=40$

$x=\frac{40}{5}$

$\boxed{x=8}$

$x-y=10$

$8-y=10$

$-y=10-8$

$-y=2$

$\boxed{y=-2}$