function calculate(){
	var f1 = document.getElementById("F<sub>1</sub>").value;
	var l = document.getElementById("l").value;
	var p1, x, b, a, ma;
	x = l/2;
	p1 = (f1 * l);
	ma = p1 * x;
	b = (ma / l) ;
	a = p1 - b;
	if (f1 != "" && l != "") {
		document.getElementById("A").innerHTML = "A: " + a;
		document.getElementById("B").innerHTML = "B: " + b;
	}
}