LINQ Groub By and Return Alias ID and GroupName as Concat Data?

Difficult title indeed. I had the data returning great until including the Group By.  I need to combine two columns data like so:

         ID = g.Key,
         Group = categoryRef.Name + "/" + categorySubRef.Name

[Output]
ID = 1, Group = Auto/Loan
ID = 2, Group = Auto/Repair
ID = 3, Group = Boat/Fuel
etc...

[code]   

var groups = 
(from c in context.CategoryAsgns
 join r in context.CategoryRefs on c.CategoryID equals r.CategoryID
 join r2 in context.CategorySubRefs on c.CategorySubID equals r2.CategorySubID
 let j = new { categoryAsgn = c, categoryRef = r, categorySubRef = r2 }
 orderby j.categoryRef.Name ascending
 group j by j.categoryRef.Name into g
 select new { ID = g.Key, 
Group = categoryRef.Name +"/"+ categorySubRef.Name) }).ToList();

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