[Solved]-How to simplify the code Using LINQ-LINQ,C#

you could try this one:

list<stockresult> stockres = item.where(x=>db.stk.any(a => a.ino == x.itemnum))
                                 select(x=> new stockresult()
                                 {
                                     itemnumber = x.itemnum,
                                     filename = x.filename
                                 }).tolist();