Paulson Corporation exchanged an old machine and $$25,500$ cash for a new machine. The old machine had a book value of $$6,000($original cost of $$28,000$ less $$22,000$ in accumulated depreciation$)$ and a fair value of $$8,200.$

Required:

a$.$ Prepare the journal entry to record the exchange. Assume the exchange lacked commercial substance.

b$.$ Briefly explain what would happen if the exchange had commercial substance. $($This is a conceptual question.$)$