How to get records from different tables

Question

Here is my Database diagram and my scenario is that When a user enter number of person and amount, amount/person
let suppose 4/1000=250 and now 250 is , match in Product_Price Field in RstProductDetails, and select only Restaurant where 250 is matched. Next when a
user select Restaurant e.g KFC and then KFC Products details is show.
Here is my [WebMethod]
[WebMethod]
    public DataSet Restaurant(decimal amount, decimal persons)
        //       DataSet result = Amount / personHash;
         //amount.ToString("amount");
        decimal price = amount / persons ;
        DataSet result = null;
        const string SQL_COMMAND_TEXT = "SELECT Product_Name,Product_Price FROM ABCD WHERE Product_Price<= @price";
        using (SqlConnection connection = Class1.GetConnection())
            connection.Open();
            using (SqlCommand command = new SqlCommand(SQL_COMMAND_TEXT, connection))
                command.Parameters.Add("@Rst_Name", SqlDbType.NVarChar);
                command.Parameters.Add("@Persons", SqlDbType.NVarChar);
                command.Parameters.Add("@price", SqlDbType.Int);
                command.Parameters["@Rst_Name"].Value = amount;
                command.Parameters["@persons"].Value = persons;
                command.Parameters["@price"].Value = price;
                using (SqlDataAdapter dataAdapter = new SqlDataAdapter(command))
                    result = new DataSet();
                    dataAdapter.Fill(result);
        return result;

Answer 1

<Table diffgr:id="Table8" msdata:rowOrder="7">
<Product_Name>Orange/Tropical Juice Small</Product_Name>
<Product_Price>120</Product_Price>
</Table>
<Table diffgr:id="Table9" msdata:rowOrder="8">
<Product_Name>Orange/Tropical Juice Tall</Product_Name>
<Product_Price>160</Product_Price>
</Table>
<Table diffgr:id="Table10" msdata:rowOrder="9">
<Product_Name/>
<Product_Price xml:space="preserve"></Product_Price>
</Table>
<Table diffgr:id="Table11" msdata:rowOrder="10">
<Product_Name>Breakfast - Meals</Product_Name>
<Product_Price>1,300</Product_Price>
<Table diffgr:id="Table16" msdata:rowOrder="15">
<Product_Name>3 pcs Hot Cakes + Small Cappuccino</Product_Name>
<Product_Price>1,370</Product_Price>
Sir when i debug mt web services it will show random items which is less than or greater than 325