Question 353149
You can use a couple of different methods:substitution, elimination, matrix inversion. 
Here's elimination.
Multiply the first equation by {{{-3}}} and add the equations together to eliminate y.
{{{9x -6y +5x + 6y =42-42}}}
{{{14x= 0}}}
{{{highlight(x=0)}}}
Now that you have {{{x}}}, use either equation to solve for {{{y}}}.
{{{0+6y=-42}}}
{{{highlight(y=-7)}}}