加减乘除

<script language="javascript">
	     var x=2
		y=4
		document.write("加法:"+(x+y)+"<br>");
		document.write("减法:"+(y-x)+"<br>");
		document.write("乘法:"+(x*y)+"<br>");
		document.write("除法:"+(y/x)+"<br>");	
	</script>