You can use this simple formula:

<b><pre><code>=AVERAGE(ArrayFormula((REGEXREPLACE(TO_TEXT(A44:H44),"L",""))*1))</code></pre></b>

Functions used:

+ [TO_TEXT](https://support.google.com/docs/answer/3094285)  
+ [REGEXREPLACE](https://support.google.com/docs/answer/3098245)
+ [ARRAYFORMULA](https://support.google.com/docs/answer/3093275)