某书商所卖的旧书中……某书商所卖的旧书中,简装书的售价是成本价的3倍,精装书的售价是成本价的4倍.某天该书商一共卖了12

1、一个旧书商所卖的旧书中,简装书的售价是成本的3倍,精装书的售价是成本的4倍.昨天,这个书商一共卖了120本书,每本书的成本都是1元钱.如果他卖这些书所得的净利润(销售收入减去成本)为300元,那么昨天他所卖出的书中有多少是简装书?有多少是精装书?

一个旧书商一个旧书商所卖的旧书中,简装书的售价是成本的3倍,精装书的售价是成本的4倍.昨天,这
个旧书商一个旧书商所卖的旧书中,简装书的售价是成本的3倍,精装书的售价是成本的4倍.昨天,这个书商一共卖了120本书,每本书的成本都是1元钱.如果他卖这些书所得的净利润(销售收入减去成本)为300元,那么昨天他所卖出的书中有多少是简装书?有多少是精装书?

一个书商所卖的旧书中,简装书的售价为成本 3倍,精装则为4倍.一天,书商共卖了120本书,成本均为1元.共得300元净利润.问：该书商卖了多少本简装,多少本精装书?

阅读理解.

There was a bookseller (书商).He did not like to pay for anything.One day a big box of books fell (掉下) on his foot. "Go to the doctor," said his wife,"and show that foot to him." "No," he said,"I'll wait until the doctor comes to our shop next time.Then I'll ask him about my foot.If I go to see him,I shall have to pay(付款)." The next day the doctor came to the shop to buy some books.The bookseller told the doctor about his bad foot.The doctor looked at it and promised (答应) to help. He took out a piece of paper and wrote something on it."Buy this medicine and put it on the foot before you go to bed every night," he said. "Thank you," said the bookseller,"And now,sir,here are your books." "How much?" asked the doctor. "Two pounds(英镑).""Oh,good," said the doctor."I shall not have to pay you anything today." "Why?" asked the bookseller. "I look over your foot.I want two pounds for that.If people come to my houses,I ask them to pay only one pound for a small thing like that.But when I go to their houses,I usually charge (收费) two pounds.And I came here today,didn't Bye-bye!"

1.The bookseller didn't want to see the doctor because ______.

A.his foot wasn't hurt. B.He couldn't go any farther C.He didn't have any money to pay the doctor D.He didn't want to pay the doctor

2.The next day the doctor came to the shop ______.

A.to buy some books B.to buy medicine C.to borrow some money D.to see the bookseller

3.The seller asked the doctor to pay ______.

A.nothing B.two pounds C.only one pound D.two pound

4.The doctor paid the bookseller ______.

A.many money B.much money C.nothing D.two pounds for books

5.Which of the following is right?

A.The seller didn't like to pay anything. B.The seller's wife didn't want him to go to the doctor. C.The seller was cleverer than the doctor. D.The doctor didn't go to the shop to buy any things.

用二元一次方程组解决问题
某种书的定价为5元每本 一书商做出以下活动方案
买1-19本每本打9折 ,超过20本（包括20本）每本7折
现在有人买两次书,共30本,共花费113元,求两次各买多少本?

一道微积分题,一个垄断者（书商）面临着一个线性需求函数x=100-p
一个垄断者（书商）面临着一个线性需求函数x=100-p,其中x 是需求（产出）,p
是价格.这个厂商的成本函数为C=25x,图书的作者可以得到每本卖出的书的销售价格的
10％作为版权费,考虑厂商的利润最大化价格和最大化利润；以及作者的利润最大化价格和最大化利润