Complex sentence: The études by Frédéric Chopin are three sets of solo studies for the piano, There are 27 overall, comprising two separate collections of twelve, numbered Opus 10 and 25, and a set of three without opus number.
Split into simpler sentences: The études by Frédéric Chopin are three sets of 27 solo studies for the piano. They comprise two separate collections of twelve, numbered Opus 10 and 25, and a set of three without opus number.