3. Tickets for all but 100 seats in a 10,000-seat stadium were sold. Of the tickets sold, 20 percent were sold at half price and the remaining tickets were sold at the full price of $2. What was the total revenue from ticket sales? A. 15,840 B. 17,820 C. $18,000 D. 19,800 E. 21,780 答案B,我选的C。轻微第一句but100什么意思,难道说是10000-100?