What is the cost, in cents, of using a certain fax machine to send n pages of a report if the total cost for sending the first k pages is r cents and the cost for sending each additional page is s cents? (Assume that n>k. ) A.r+s (n-k) B.r+s (n + k) C.rs (n + k) D.kr+s (n-k) E.kr+ns
A.r+s B.r+s C.rs D.kr+s
【参考答案】
A 解析：用某台传真机发送n页的报告，若最初k页总计费用为r美分，每额外多一张加收s美分，则以美分为单位使用该传真机发送n页报告需多少钱?(假设n>k) 解：本题的正确答案为(A)。最初k页总共花r美分，其余(n-k)张共花s(n-k)美分，因此发n页共需r+s(n-k)美分。