Question 1006299
Try Elimination Method.  Multiply first equation by 3, and multiply second equation by 4:


{{{system(12x-21y=30,12x+8y=-28)}}}


{{{12x-21y-(12x+8y)=30-(-28)}}}
{{{-29y=58}}}
{{{highlight(y=-2)}}}


You can continue Elimination of y, but using factors of 2 and 7, same order.
{{{system(8x-14y=20,21x+14y=-49)}}}
but for this part, ADD the corresponding members.....
find x.