Problems that may occur when entering a parkway are: cars not yielding or moving over for oncoming traffic, cars not obeying the speed limit and cars not keeping up with the flow of traffic. It is important to make sure you check your surroundings multiple times when entering a parkway because you are coming into traffic that has been moving at a much faster rate and trying it merge in with them. 
        
             
        
        
        
Answer:
See explanation section
Explanation:
(a) December 1     Cash             Debit    $18,000
                         Unearned revenue      Credit    $18,000
<em>Note: The company received the money in advance for a contract to do during December to April. Therefore, they received cash while a liability increased due to receiving advance money.</em>
(b) December 31   Unearned revenue     Debit    $3,600
                             Service revenue           Credit    $3,600
<em>Note: As the company started performing, after the completion of 1st month, i.e., December 1 to December 31, the advance money started expiring because of providing services. Moreover, as the service is performed evenly for 5 months, the 1st month's revenue = $(18,000/5) = $3,600.</em>
 
        
             
        
        
        
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