What are some of the challenges in deciphering what is on ancient papyrus?

The challenges of deciphering things that were written on ancient papyrus was in part due to the ancient Egyptians having a different alphabet compared to what is commonly used today, where each word, which depicts a certain meaning, is created out of multiple alphabetic characters. In ancient Egypt symbols themselves usually denoted meanings. Another problematic is the quality of these papyri today. 

Ais 190 b is 200c it can't be more then 100%