In addition to translating greek writings and writing his own ideas about mathematics and music, also wrote the fundamentals of music.

I believe the correct answer is Boethius.

Anicius Manlius Severinus Boëthius, Roman senator and philosopher, wrote the fundamentals of music while translating Greek writings and writing his own ideas about mathematics. Boethius' “De institutione musica” was the fundament of music, in which he introduced the threefold classification of music: musica mundane (music of the world), musica humana (harmony of human body and spiritual harmony) and musica instrumentalis (instrumental music).

Boethius

Explanation:

its the answer for apex