できた

<html>
<head>
<script language="javascript">
function calc() {
var b = document.getElementById("b").value;
var s = document.getElementById("s").value;
var c = document.getElementById("c").value;
var r = -3+((10/b)+(12/s)+(2/c)+0.44)/5;
document.getElementById("result").value = r;
}
</script>
</head>
<body>
b=<input type="text" name="b" value="" id="b"><br>
s=<input type="text" name="s" value="" id="s"><br>
c=<input type="text" name="c" value="" id="c"><br>
<input type="button" value="計算" onclick="calc();"><br>
<input type="text" name="result" value="" id="result"><br>
</body>
</html>