尝试访问同一函数中的变量时切换中的未定义错误

function myFunction() {
  var y = parseInt(document.getElementById("txt1").value);
  var z = parseInt(document.getElementById("txt2").value);
  var b = parseInt(document.getElementById("txt3").value);
  var x = (52 * y) + (52 * z) + b;
  document.getElementById("demo").innerHTML = x;

  var five = parseInt(document.getElementById("txt5").value);
  var six = parseInt(document.getElementById("txt6").value);
  var seven = parseInt(document.getElementById("txt7").value);
  var eight = document.getElementById("txt8").value;

  var utEtt = x * 0.10;
  var utTva = utEtt * eight;
  var utTre = utTva * five;


  /*document.getElementById("print1").innerHTML = utTre;
  alert(utTre);*/

  var valj = document.getElementById("selecting");
  var valjValue = valj.options[valj.selectedIndex].value;


  switch (valjValue) {

    case 'all':
      var result1 = "Gas/Petrol consumption is: ".utTre;
      document.getElementById("print1").innerHTML = result1;
      break;
  }
}