How Do I Convince My Parents To Let Me Travel Overseas Without Them?

I finally convinced my friend to travel with me to Beirut, Lebanon, but the problem is her parents. I need to know how she can convince them to let her travel with me, my older brother (16), and possibly my grandma.My brother has taken me to and back from lebanon 2 years in a row, and its pretty easy to us. And she says her parents think lebanon would be a good expirience for her(her being a muslim, lebanon being a part-muslim country), but they just mentioned that a loooong time ago when they didnt even think she would come with me. and im aware of the money situation as well! I need and answer as soon as possible! Thanks!!