Please explain the solution to this general accounting problem using the correct accounting principles.

Eagle Enterprises sold a business asset with an adjusted tax basis of $45,000 for a total price of $120,000 in 2010. The buyer paid $40,000 in cash and gave a promissory note for the $80,000 balance. Eagle used the installment sale method to recognize the gain. By 2013, the buyer had paid $20,000 in principal on the note, and in that year, Eagle sold the remaining note balance to a third party for its face value of $60,000. Calculate the total gain on the sale