How do I confront my mother about gambling, without pissing her off?

My life is complicated, for one reason, knowing that my mother is addicted to gambling. I know because of my age I might not need to care, but because of my father's age I definitely do. My dad is 60 as of right now. He came into America about 20 years ago. He and my mom found this house 10 years ago. My Mom is putting $15,000 a year in MGM's pocket. They only have $100,000 to pay off. They also have my older brothers' college fees to pay off. Soon enough mine. I'm just worried about it, about my Mom. I tried to show her one reason not to go, that reason was the Lord. You'd be surprised what the Bible says about luck and gambling. I tried to show it to her today, and she simply said, "Go away." What's a better way to rid her of this addiction of the casinos. Just to let you know, she usually goes four days out of the seven in a week. What should I say when I try to get her to read something that'll get her away from the casino. Of course without getting her pissed off. (All answers are helpful.)