Script program to count only alphabetical characters

Use and complete the template provided. The entire template must be completed. If you don't, your post may be deleted!

1. The problem statement, all variables and given/known data:
   Write a shell script program to count the ONLY the number of alphabetic characters stored in the shell variable call count. Use count='The answer (12345) you should get is 24' as you variable and value. Use the sed command as part of your solution. Put you tested program in the space below. The logic of this program is the same as the last program, but you use sed to remove the characters you don't want to count and to leave and count only the alphabetic characters that are left.

2. Relevant commands, code, scripts, algorithms:
   wc -m count, must use sed.

3. The attempts at a solution (include all code and scripts):
   count | sed wc

4. Complete Name of School (University), City (State), Country, Name of Professor, and Course Number (Link to Course):
   Calvin College, Grand Rapids MI, USA, Mr. Johnson, CO 142.

Note: Without school/professor/course information, you will be banned if you post here! You must complete the entire template (not just parts of it).

You pipe commands into other commands, you don't pipe variables.

Variables don't work just by typing their name, you have to put a $ in front of them.

'sed wc' makes no sense at all.

It'd look something like echo $count | sed '...' | wc

You will need to figure out what regular expression will remove non-alphabetic characters, and how to use wc to count characters(see man wc)