The 606-10-25-12 is the correct answer. However, I am really confused for how to get it.

For example, what should I do to calculate to get the answer 606?

tbs.res.revrecog.contra.mod.001_0318 4 RETURN TO YOUR ANSWER . On February 21, 20X1, Questions Inc. signed a contract with Testing 123 Corp. The initial terms of the contract require Questions Inc.to to write 100 questions for Testing 123 Corp's National testing review course. In return, Testing 123 Corp will pay Questions Inc. $25 per question. On March 12, 20X1, after Questions Inc. has submitted 75 questions, both parties agreed to a change in the contract terms. The new terms provide that Questions Inc. will provide an additional 50 questions for $30 per question. Which section of the authoritative literature addresses the amount of revenue that Questions Inc. should recognize for the remaining questions to be submitted? Enter your response in the answer fields below. Guidance on correctly structuring your response appears above and below the answer fields. Enter your response in the answer fields below. Guidance on correctly structuring your response appears above and below the answer fields. FASB ASC 606 10 25 12