单项选择题
A.780米 B.800米 C.850米 D.900米
A.480/x+10=480/(x+4) B.480/x-10=480/(x+4) C.480/x+10=480/(x-4) D.480/x-10=480/(x-4)
A.1222 B.1232 C.1322 D.1332