Final answer:
The decree inscribed on the Rosetta Stone is a royal proclamation affirming the divine status of King Ptolemy V. It is written in hieroglyphics, demotic, and Greek, and was deciphered using the Greek inscription on the stone.
Step-by-step explanation:
The content of the decree inscribed on the Rosetta Stone is a royal proclamation affirming the divine status of King Ptolemy V. The decree was passed by a council of priests on the first anniversary of his coronation. It is written in three scripts: hieroglyphics, demotic, and Greek. The Greek inscription on the stone was instrumental in deciphering the other scripts, leading to a greater understanding of Egyptian society and culture.