for MJ

mile.js

function calculate() {
  var total_miles = 0;
  var avg_daily_miles = 0;
  for (var i=1; i<=7; i++) {
    var dist = +document.getElementsByName("value" + i)[0].value;
    total_miles += dist;
    avg_daily_miles += dist/7.0;
  }
  document.getElementById("totalM").value = total_miles;
  document.getElementById("avgM").value = avg_daily_miles;
  var total_gas = +document.getElementById("gas1d").value + +document.getElementById("gas2d").value + +document.getElementById("gas3d").value - +document.getElementById("gas4d").value;
  document.getElementById("totalG").value = total_gas;
  document.getElementById("mpgL").value = (total_miles/(+document.getElementById("gas2d").value + +document.getElementById("gas3d").value));
};