Respuesta :
Tybalt is to blame because he kills Mercutio which causes Romeo to burst out in anger and kill Tybalt which then causes Romeo to be exiled.
Tybalt is to blame because he wouldn't leave Mercutio alone, whenever all he was trying to do was find Romeo. So once he fought Mercutio, and killed him, he made Romeo feel as if he had to get back at Mercutio by fighting him.