On July 15, Zink Jewels agrees to a contract to sell 4,000 promise rings for $100,000 to Costless Stores, Inc. On October 1, after 2,000 rings pair of have been delivered, Zink and Costless modify the agreement to reduce the price of the remaining 1,000 rings to $12 each. During October, Zink Jewels delivers 600 rings. How much revenue will Zink recognize for the month of October?

A) $3,300

B) $7,200

C) $13,050

D) $2,175

I need the solution and the work for this problem.