I have done all my journal entries for this particular problem, but I cannot figure out the last one.

It says "sale of finished goods costing $531,400 for $1,250,000 in cash." Someone please help me through this

You sold the goods for 1.25 mil that cost 531,400.

Credit 1, 250,000 to sales, and debit 531,400 to COGS expense acct.
The difference between cogs annd sales is gross profit, and after all expenses is net profit.

To record the sale:
Debit Cash for 1,250,000
Credit Sales Revenue for 1,250,000

Debit COGS for 531,400
Credit Finished Goods Inventory for 531,400