Usually Cassandra tap dances 1 7/8 hours a day. Today she reduced this time by half. For how long did she tap dance today?

Answer

15/16 hours

Q: What is half of 1 7/8? A: Half of 1 7/8 is 15/16.
Q: How many hours did Cassandra tap dance today? A: Cassandra tap danced for 15/16 hours today.