Is anyone able to help me?

I'm working across 3 columns. (A, B, C) and 3 worksheets

In column A, it adds up the total of "X" across 3 worksheets. If the "X"'s amount to 8 then it will return a value of "M" - This is fine.

In column B, if column A displays "M", then column B will return a BLANK "", if column A is <7 I want it to add up the total from across the 3 worksheets and output the total - both of these are fine, however if the total from across the 3 sheets=8, I want the output to be "M".

This is the formula I have so far:

=IF(K4="M","",COUNTIF('I can (+ & -)'!AG6:AL6,"X")+COUNTIF('I can (x & ÷)'!L6:W6,"X")

How do I add the final part where the output will be "M" if total =8?