function calc(){

	

	if (document.getElementById("x1").value != "" ){

		rez_exact = parseFloat(document.getElementById("x1").value) * parseFloat(document.getElementById("c1").value) / parseFloat(document.getElementById("c2").value);



	if (document.getElementById("co").value != "" ){

		comision = (100 + parseFloat(document.getElementById("co").value)) / 100;

		rez_exact = parseFloat(document.getElementById("x1").value) * parseFloat(document.getElementById("c1").value) / parseFloat(document.getElementById("c2").value) * comision;

			

		}

		

		document.getElementById("rez").value = Math.round(rez_exact*100)/100;

		document.getElementById("tva").value = Math.round(rez_exact*100*0.24)/100;

		document.getElementById("rez_final").value = Math.round(rez_exact*100*1.24)/100;

	}

	else

	{

		document.getElementById("rez").value = "";

		document.getElementById("tva").value = "";

		document.getElementById("rez_final").value = "";

	}

}