Helo!!, i need, help me please i'm confused with this query, sorry for my english :(

I have this query and work fine

$mensajes = DB::table('users as U')
            ->where('R.c_id_fk', '=', $c_id)
            ->leftJoin('mensajes_reply as R', 'R.user_id_fk', '=', 'U.id')
            ->select('R.cr_id as id_mensaje','R.time as fecha','R.reply as mensaje','U.primer_nombre as nombre','U.apellido_paterno as apellido')
            ->orderBy('R.cr_id', 'asc')
            ->take(10)
            ->get();

But i take last 10 rows with orderby desc, but show data i need in ordeby asc, i try with raw how read in old forum but y can't understand how convert this to raw form how this

$users = DB::table(DB::raw('('.
    DB::table('foo')->orderBy('bar', 'desc')->take(10)->toSql()
.') foo'))->orderBy('bar', 'asc')->get();

Because i use name as other name and this confused me

Thanks!