Input variables - a noob's plea

hey,

the thing is, im trying to get me program to take a variable set by the user and apply it to
a formula, within another variable. So when the button is clicked and the user has inputted
their number, the number gets subbed into this formula that makes another variable. This is what i have so,

this.submit.onRelease= function() {
fractal();
}
this.submit.onRelease = function() {
anglex=input_txt.text;
}

This is the ‘thing’ that tells the function to ‘go’. The function works if a substitute a value
instead of a variable

Any help, hints or tips would be greatly appreciated
(p.s. this is my first post so if im doing anything wrong please tell me)