For each of the following transactions and economic events, prepare the necessary journal entries. Provide a brief explanation for each journal entry and state any assumptions you make.

a. Inventory costing \($20,000\) is purchased on credit.

b. Inventory costing \($15,000\) is written off because it has become saleable.

c. Inventory costing \($10,000\) is sold to a customer for \($22,000\) cash. The entity uses a periodic inventory control system.

d. Inventory costing \($8,000\) is sold to a customer on credit for \($20,000\), with the amount due in 30 days. The entity uses a perpetual inventory control system.

e. Management discovers that the NRV of its inventory is \($200,000\) and its cost is $215,000.

f. A supplier is paid \($5,000\) for inventory purchased on credit.

g. Inventory on hand was written down in the previous period by \($50,000\). The NRV of that inventory has since increased by \($30,000\). All inventory from the previous period is still on hand.