misi para master javascript, ane binggung nih lagi buat program menghitung rata2 nilai tapi pake % gagal mulu
<html>
<head><title>aaaa</title></head>
<body>
<table border="1" width="600" height="500" cellpadding="1" align="center">
<tr>
<td width="50" height="50" align="center" bgcolor="orange"><font face="Baskerville Old Face" size="10" color="black"><b>NILAI</b></font></td>
</tr>
<tr>
<td width="200" valign="top" align="center" bgcolor="orange" ><font face="Comic Sans MS" size="4" color="black"><b>HASIL NILAI</b></font>
<br>
<br>
<table border="5" width="400" size="10" bgcolor="white" bordercolor="black" cellpadding="5" cellspacing="0" >
<tr>
<td width="100" align="center" bgcolor="white"><b>NPM</b></td>
<td width="100" align="center" bgcolor="white"><b>NAMA</b></td>
</table>
<br>
[removed]
function rata(){
var a=parseInt(l.a.value);
var b=parseInt(l.b.value);
var c=parseInt(l.c.value);
var d=parseInt(l.d.value);
var rata=(a+b*20%)+(c*40%)+(d*40%)/4;
l.r.value=rata;
}
[removed]
<body>
<CENTER>
<form name="l">
<table>
<tr><td>Nama</td><td><input type="text"></td></tr>
<tr><td>Npm</td><td><input type="text"></td></tr>
<tr><td>Nilai Quis1</td><td><input type="text" name="a"></td></tr>
<tr><td>Nilai Quis2</td><td><input type="text" name="b"></td></tr>
<tr><td>Nilai UTS</td><td><input type="text" name="c"></td></tr>
<td>Nilai UAS</td><td><input type="text" name="d"></td>
</tr>
<tr>
<td> Hasil</td><td><input type="text" name="r" READONLY></td>
</table>
</form>
<input type="button" value="Hitung">
</body>
</FORM>
<br>
</tr>
</table>
</body>
</html>
kalo sampe jalan programnya 