Mx.transitions.Tween Question

Hi,
I am hoping someone can help me with this movieclip motion thang. I just need to have this movie clip start where it left off (instead of var begin = 50;) everytime. So when I add this same code in FRAME 2, it will grab the movieclip where it was left and position it somewhere else. Any ideas? Maybe a setting a variable, I dunno.

thanks,
h

FRAME 1

myButton_btn.onRelease = function() {
tweenBall(mx.transitions.easing.Back.easeOut);
};
function tweenBall(easeType) {
var begin = 50;
var end = 380;
var time = 20;
var mc = ball_mc;
ballTween = new mx.transitions.Tween(mc, “_x”, easeType, begin, end, time);
}