Query using Where Condition with Entity Framework

Hi,
I am trying to match the ID from two tables in the where condition  using EF,  I am getting an Error " Non-Static Method Requires a Target. Please see my query below
 var result = db.Invoices.Include(f => f.Programs).Where(f => f.InvoiceID == inv.InvoiceID && f.Programs.ID == inv.Programs.ID).ToList();

if(result.Count > 0)
{
....... code for this condition..
}

Thanks for your help.