text: 
  function total(inputBill, inputTip){
       inputBill = document.getElementById("bill").value;
       inputTip = document.getElementById("tip").value;
       
       let totalTip = parseFloat((inputBill * (inputTip / 100))).toFixed(2);
       let totalAmount = +inputBill + +totalTip;
       let letters = /^[a-zA-Z]+$/;
  
       if(inputBill.match(letters) || inputTip.match(letters)){
          totalTip = document.getElementById("tipping").innerHTML = "$" + 0;
          totalAmount = document.getElementById("grand").innerHTML = "$" + 0;
      }else{
         totalTip = document.getElementById("tipping").innerHTML = "$" + totalTip;
         totalAmount = document.getElementById("grand").innerHTML = "$" + totalAmount;
       }
      return  totalAmount;
  }
  
  function dividingTotal(inputBill, groupTotal){
      inputBill = document.getElementById("bill").value;
      groupTotal = document.getElementById("groupAmount").value;
  
      let letters = /^[a-zA-Z]+$/;
      let divideMeal = parseFloat(inputBill / groupTotal).toFixed(2);
     
      if(inputBill.match(letters) || groupTotal.match(letters)){
           totalAmount = document.getElementById("displayTotal").innerHTML = "$" + 0;
      }else{
          totalAmount = document.getElementById("displayTotal").innerHTML = "$" + divideMeal;
      }
      return divideMeal;
  }