$1]$ File with floats

Read from the user float numbers $($maximum $10,$ use an array$).$ Stop reading when the user introduces a

negative number.

Write the numbers to the text file "numbers.txt$"($text file$).$

Next create another program to read the numbers $($variable size, use feoff$)$ function$).$

The numbers must be averaged. Display the average.

$2]$ Add the count

Suppose you have a text file like this:

$3$

Alice in Chains

Yellow Submarine

The show must go on

Where the first number indicates the number of lines $($can be a different number$)$

Make a program to read the file for read, close he file, count the letters, open the file again to append, and

write a message saying how many letters it has, so the file will end like this:

$3$

Alice in Chains

Yellow Submarine

The show must go on

The lines have $50$ letters.

c programming please