Question

{x = 3y +10 2x + 3y =0

Answer 1

$\begin{cases}x=3y+10\to~~ja\´~~temos ~~uma~~inco\´gnita ~~isolada\\ 2x+3y=0\end{cases}\\ \\\\\\2(3y+10)+3y=0\to ~~6y+20+3y\to~~6y+3y=-20\to\\ \\ 9y=-20\to~~ \boxed{y=-~ \frac{20}{9}} \\ \\\\\\x=3y+10\to~~x=3.( -~\dfrac{20}{9} )+10\to~~ x=-~\dfrac{60}{9} +10\to\\\\ x=~ \dfrac{-60+90}{9} \to~~ \boxed{x=~ \dfrac{30}{9}}\\\\\\\\ \large\boxed{\boxed{S=\left\{ \frac{30}{9} ~; ~-\frac{20}{9} ~\right\}}}$