Question

10x+3y=-27; x+y=-9
Sacar la igualación

Answer 1

$\left \{ {{10x+3y=-27} \atop {x+y=-9}} \right.$

$\left \{ {{x=\frac{-27-3y}{10} } \atop {x=-9-y}} \right.$

$\frac{-27-3y}{10} =-9-y$

-27-3y=-90-10y

10y-3y=-90+27

7y=-63

y=-9

x=-9-(-9)

x=-9+9

x=0