Complex sentence: She began studying magick and witchcraft at the age of 16 and was initiated into the Ordo Templi Orientis, a Thelemic religious organization, at age 21.
Split into simpler sentences: She began studying magick and witchcraft at the age of 16. Also, she was initiated into the Ordo Templi Orientis, a Thelemic religious organization, at age 21.