Answer
$x=\frac{10}{7}$
$y=-\frac{5}{7}$
Work Step by Step
First, we have to solve the second equation for $x$ and after that, we can substitute this expression in the first equation:
$3x+6y=0$
$3x=-6y$
$x=-2y$
$-3x+y=-5$
$-3(-2y)+y=7y=-5$
$y=-\frac{5}{7}$
$3x=-6y=\frac{(-6)\times (-5)}{7}\frac{30}{7}$
$x=\frac{10}{7}$
We need to check, if it is the right solution, we substitute x with $\frac{10}{7}$ and y with $-\frac{5}{7}$:
$-3(\frac{10}{7})+(-\frac{5}{7})=\frac{-35}{7}=-5$ $\checkmark$
$3\frac{10}{7}+6(-\frac{5}{7})=0$ $\checkmark$