A.$435,000 B.$645,000 C.$765,000 D.$810,000
A.$13和$26,000 B.$13和$20,000 C.$23和$20,000 D.$23和$46,000
A.1,500個(gè) B.2,700個(gè) C.7,800個(gè) D.9,000個(gè)