Can this be calculated in acrobat?

Use this:

var x = Number(this.getField("Rating").value);
var x2 = Math.pow(x, 2);
var al = Number(this.getField("AreaLevel").value);
var al2 = Math.pow(al, 2);
var hf = (.1*x)+(.001*x2);
var lf = 10+(.5*al)+(.05*al2);
var f = (hf/lf)+1;
var f1 = (1/f);
event.value = (1-f1)*.8;

EDIT: if you want it  to be more precise use this:

var x = Number(this.getField("Rating").value);
var x2 = Math.pow(x, 2);
var al = Number(this.getField("AreaLevel").value);
var al2 = Math.pow(al, 2);
var hf = (.1*x)+(.001*x2);
var lf = 10+(.5*al)+(.05*al2);
var f = (hf/lf)+1;
var f1 = (1/f);
if(al<15){
event.value = (1-f1)*.797;
}else if(al<27){
event.value = (1-f1)*.787;
}else if(al<34){
event.value = (1-f1)*.775;
}else if(al<43){
event.value = (1-f1)*.767;
}else if(al<48){
event.value = (1-f1)*.758;
}else if(al<60){
event.value = (1-f1)*.749;
}