var pret_total=0;
var operation='+';

function calc_pret(id){
  //eval("operation=(document.calcFrm."+id+".checked?'+':'-')")
  //eval("pret_total=pret_total"+operation+"parseInt(document.calcFrm."+id+".value)");
  //document.getElementById('div_pret_total').innerHTML=pret_total;
}