Final answer:
The number of minutes Chloe practiced today cannot be determined without knowing the duration of her longest practice session previously. We can only say she practiced for 30 minutes longer than that unknown number.
Step-by-step explanation:
The question does not provide the actual number of minutes Chloe practiced on the night she played the most songs. To answer how many minutes Chloe practiced today, we require that initial number. For instance, if Chloe practiced for 60 minutes on the night she played the most songs, then today she practiced for 60 minutes + 30 minutes extra, which would amount to 90 minutes in total. However, without the actual number of minutes from the reference night, we cannot calculate today's practice time.