Answer:
The right thing to do when invited to a wedding banquet is you mustn't loath it, because it is a blessing. Declining a blessing means declining the king, so you'll be the one to suffer if you ran out of blessing.
The king in the parable get angry because the invited guest's refused to come. And, they badly don't want to attend the banquet so they committed a horrible sin and that is to kill the king's servants.
Explanation:
Sorry that's all I've got.