## Algebra 1: Common Core (15th Edition)

We know that $y=-2x+6$. Thus, in the second equation, wherever we see y, we will substitute -2x+6, and then we will solve: $3(-2x+6) -x +3 =0 \\\\ -7x+21=0 \\\\ -7x =-21 \\\\ x=3$ We now substitute x=3 back in: $y=-2(3)+6=0$ We plug our values for x and y back into the first equation and confirm that our answer is, indeed, correct.