var sum=0; //suma ECTS
var mulSum=0; // suma ECTS * ocena
$('td[title="ocena"]').each(function(){
if($(this).text() === "---"){
    //do nothing
}else{
    mulSum += parseFloat($(this).text()) * parseFloat($(this).next().next().text());
    sum += parseFloat($(this).next().next().text());
    console.log(parseFloat($(this).text()), parseFloat($(this).next().next().text()));
}
});
console.log("Suma ECTS * ocena:", mulSum);
console.log("Suma ECTS:", sum);
console.log("Srednia: ", mulSum/sum);