Joan is selling handmade bead necklaces at a local art fair. She paid $250 to reserve her booth. The cost of supplies for each necklace averages $2. So, her cost, y, for x necklaces is represented by y=$250+2x. If she sells her necklaces for $12, her revenue, y, is represented by y=12x. Use the system of equations to find how many necklaces Joan needs to sell to break even.