7. The asking price table for determining the concurrent price is as follows. What was the initial price? The selling quantity is from right to left, and the buying quantity is from left to right in chronological order. Sales volume Price Purchase quantity 20,000 1,000 300 2,000 19,000 500 500 800 18,000 400 200 600 200 300 400 17,000 300 200 400 300 500 16,000 600 400 1000 15,000 1,000 2,000 800 400 600 14,000 4,000 2,000 300 13,000

No answer 18,000 17,000 15,000 16,000