audio book--RMS level at 25.7 --I need it at about 20

You can try Audiobook Mastering version 4.

It boils down to three Audacity effects tools and a custom measuring tool.

If you’re work is relatively quiet, it’s one pass through the three tools and out the door. Please don’t ad-lib or scramble the tools, they work in order. If you’re already close, they will give you an ACX reading in the middle of the specifications, match and still sound like you.