Entity framework: edit view model

     public partial class SALES
      {
        [key]
        public int id_sales { get; set; }
        public DateTime offer_dateC { get; set; }
        public int comnamC { get; set; }
        public string sales_contactC { get; set; }
        public string prod_name_pharma_formC { get; set; }
        public virtual ICollection<PRICE> PRICE { get; set; }
        public virtual ICollection<COUNTRIES> COUNTRIES { get; set; 
      }

public partial class PRICE
    {
        [Key]
        public int id_price { get; set; }
        public decimal priceC { get; set; }
        public string strengthC { get; set; }
        public string quantity { get; set; }
        public string currency { get; set; }
        public virtual SALES SALES { get; set; }
    }

public partial class COUNTRIES
    {
        [Key]
        public int id_country { get; set; }
        public string countryC { get; set; }
        public string coountry_name { get; set; }
        public virtual SALES SALES { get; set; }
    }

public class myViewModel
    {
      [Key]
      public int id_offers { get; set; }

      public DateTime offer_dateC { get; set; }
      public int comnamC { get; set; }
      public string sales_contactC { get; set; }
      public string prod_name_pharma_formC { get; set; }
      public List<decimal> priceC { get; set; }
      public string strengthC { get; set; }
      public string quantity { get; set; }
      public string currency { get; set; }
      public List<string> countryC { get; set; }
    }