Given the task definition and input, reply with output. In this task, you're given a passage, further information available on a particular linked term from the statement, and a question. Your job is to generate the answer to the question by using the information provided. If there is no clear answer obtainable, output 'none'.

Passage: His role during the reign of his father is unknown. He first appears as the protovestiarios (chamberlain) of Constantine VII Porphyrogennetos (r. 913959), the legitimate emperor of the Macedonian dynasty, but it is unclear whether it was Romanos Lekapenos who appointed him to the post or whether Constantine VII gave it to him after Romanos' downfall. The contemporary Theophanes Continuatus reports that Basil was a loyal and dedicated servant of Constantine VII, and had a close relationship with Constantine's wife, and his own half-sister, Helena Lekapene. Following the deposition of Romanos Lekapenos in December 944, Basil supported Constantine VII when he regained power from Basil's half-brothers Stephen Lekapenos and Constantine Lekapenos in January 945, and was rewarded with senior titles and offices: in his seals and dedicatory inscriptions he is called a basilikos, patrikios, "paradynasteuon of the Senate" (likely a distortion indicating the combined titles of paradynasteuon and protos, "first", of the Senate), as well as megas baioulos (grand preceptor) of Constantine's son and heir, the future Romanos II (r. 959963). In ca. 947/8 he was raised further from protovestiarios to parakoimomenos (head chamberlain), in succession to Theophanes.
Link Information: none Question: How old was Basil Lekapenos when he joined on as the chamberlain of Constantine VII Porphyrogennetos?
Answer: none