function AvgPriceCalcu(){
	var R1, R2, R3, R4, R5
	var inv=false
	a1=document.calcu.txtavg1.value;
	a2=document.calcu.txtavg2.value;
	v1=document.calcu.txtvol1.value;
	v2=document.calcu.txtvol2.value;
	if (isNaN(a1)==true || a1==""){
		inv=true
		document.calcu.txtavg1.focus;
	}
	if (isNaN(a2)==true || a2==""){
		inv=true
		document.calcu.txtavg2.focus;
	}
	if (isNaN(v1)==true || v1==""){
		inv=true
		document.calcu.txtvol1.focus;
	}
	if (isNaN(v2)==true || v2==""){
		inv=true
		document.calcu.txtvol2.focus;
	}
		
	R1=v1 * a1
	R2=v2 * a2
	R3=R2 - R1
	R4=v2 - v1
	R5=R3 / R4
	if(inv==true){
		document.calcu.result.value="Invalid"
	}else{
		document.calcu.result.value=R5
	}
}