Prepayments by customers. Greenland Enterprises began a new magazine in the fourth quarter of 19X2. Annual subscriptions, which cost $18 each, were sold as follows: Number of Subscriptions Sold October 400 November 700 December 1,000 If subscriptions begin (and magazines are sent) in the month of sale: a. Present the necessary journal entry to record the magazine subscriptions sold during the fourth quarter. b. Determine how much subscription revenue Greenland earned by the end of 19X2. c. Compute Greenland's liability to subscribers at the end of 19X2.