Answer:
the question is missing the amount received by Trevor, but we can solve using a number that we choose:
For instance, lets say that Trevor received $6,000 for legal services to be performed during 6 months. The journal entry to record this would be:
August 1
Dr Cash 6,000
Cr Unearned revenue 6,000
On December 31, the adjustment entry should be:
Dr Unearned revenue 5,000
Cr Service revenue 5,000
Unearned revenue is a liability account because we received money but we owe the services, therefore, revenue will only be recognized as the legal services are performed.