how to return value from store procedure to entity frame work linq

Question

SELECT SUM(Quantity) as Quantity FROM tblcart where Username =@Username and MenuId= @MenuId and KitchenId= @KitchenId and MenuStatus=0

end

public IEnumerable<MenuModel> GetKitchenMenuOnCartAdd(int? kid, string Username, int? menuid)
{
    var GetMenu = db.tblMenus.Where(a => a.KitchenId == kid && a.MenuId == menuid).Select(a => new MenuModel
    {
        MenuId = a.MenuId,
        Name = a.Name,
        Description = a.Description,
        Discount = a.Discount,
         //not getting the return value in button status
          -----> 
       ButtonStatus = db.spSumCart(Username, menuid, kid).FirstOrDefault(),
    }
    ).ToList();
    return`GetMenu;
}