I started by decoding a few letters (like space and e) but then noticed that lower case and upper case letters starting the same which cut the number needed down and then noticed after key letters like a, e, t, h, that the code was sequencing: 5c was e; ac was a; 3c was d; 4c was d. So the number would increase on each letter for c until 9 and by that point i had 18 from that alone plus other key letters along the way with doing most common letters for missing words like "the", "and", "are" etc.
![mmontgomery_0-1655313353719.png mmontgomery_0-1655313353719.png](https://community.alteryx.com/t5/image/serverpage/image-id/240327i9D5C2EC13C693551/image-size/medium?v=v2&px=400)