I don’t know how to get my button to calculate. Please help.
<HTML>
<HEAD>
<TITLE>Get Your Grade</TITLE>
</HEAD>
<BODY>
<h1>Calculate Your Cyber Grade</h1><br>
<FORM name="b" onsubmit="return false;">
<h2>Homework Average:</h2><br><INPUT type="number" name="hw" value=""><br>
<h2>Lab Average:</h2><br><INPUT type="number" name="lab" value=""><br>
<h2>Six Weeks Exam:</h2><br><INPUT type="number" name="six" value=""><br>
<h2>Twelve Weeks Exam:</h2><br><INPUT type="number" name="twelve" value=""><br>
<h2>Final Exam:</h2><br><INPUT type="number" name="final" value=""><br>
<h2>Instructor Option:</h2><INPUT type="number" name="inst" value=""><br>
<br><br><h2>Final Grade:</h2><INPUT type="number" name="c" value="a">
<INPUT type="button" value="Get That Grade!"
onclick="var a = document.forms.b.c.value;
document.forms.b.c.value = (document.forms.b.hw.value * .15+document.forms.b.lab.value* .15+document.forms.b.six.value * .15+document.forms.b.twelve.value * .15+document.forms.b.final.value * .3+document.forms.inst.value * .1) / 6;">
</FORM>
</BODY>
</HTML>