Create an application class named LetterDemo that instantiates objects of two classes named Letter and CertifiedLetter and that demonstrates all their methods. The classes are used by a company to keep track of letters they mail to clients. The Letter class includes auto-implemented properties for the Name of the recipient and the Date mailed (stored as strings).Next, include a ToString() method that overrides the Object class’s ToString() method and returns a string that contains the name of the class (using GetType()) and the Letter’s data field values. Create a child class named CertifiedLetter that includes an auto-implemented property TrackingNumber (of type string) that holds a tracking number for the letter.

The purpose of this problem is to write some small functions and practice passing things around amoung functions.1) the main function shall ask the user to enter three numbers and read the three numbers.2) write a function named findsum that takes three numbers as arguments and returns their sum. the main function shall call this function.3) write a function named findaverage that takes the sum and the number of numbers and returns the average. the main function shall call this function.4) write a function named findsmallest that takes the three numbers and returns the smallest value. the main function shall call this function.5) the main function shall print the results in the following format, with two decimal positions and the decimal points aligned: