Hopeing someone can solve this for me.

I am trying to create variables to hold totals - in this case "Friday__c" hold either nothing or a decimal data type.  The query builds a list which I use in my visualforce page.  I would like to iterate through the list and add up all "Friday__c" fields into the variable totalFridayHours then display this field on my visualforce page.

I get the "Arithmetic Expression must use numeric arguments error in my "For" statement near the bottom of my code:
 

public class fetchTimeCardEntryDataController {

    public String datename{get;set;}
    public List<Time_Card_Entry__c> TEList{get;set;}
    public Decimal totalFridayHours {get;set;}
    public String query{get;set;}
    public dummyTable__c dum{get;set;} 


    public fetchTimeCardEntryDataController() {
        dum=new dummyTable__c();
    }

    public PageReference fetch(){
    
        Date sDate = dum.dateOne__c;
        Date eDate = dum.dateTwo__c;
    
        String SobjectApiName = 'Time_Card_Entry__c';
        Map<String, Schema.SObjectType> schemaMap = Schema.getGlobalDescribe();
        Map<String, Schema.SObjectField> fieldMap = schemaMap.get(SobjectApiName).getDescribe().fields.getMap();
 
        String commaSepratedFields = '';
        for(String fieldName : fieldMap.keyset()){
            if(commaSepratedFields == null || commaSepratedFields == ''){
                commaSepratedFields = fieldName;
            }else{
                commaSepratedFields = commaSepratedFields + ', ' + fieldName;
            }
        }
      query = 'select ' + commaSepratedFields + ' from ' + SobjectApiName + ' Where Monday_Date__c >=:sDate AND Monday_Date__c <=:eDate  Limit 500';

     System.debug('query:'+query);

        TEList = Database.query(query);
         // Process the totals

//************ERROR IN THIS BLOCK *******************

         for(Time_Card_Entry__c tec1 : TEList) {
         
         if(TEList.Friday__c!=null) {
             totalFridayHours += time_card_entry__c.Friday__c;
           }
         
         }

        return null;
    }
}