There are several books on each shelf. If you take five books from shelf B and put them on shelf A, the number of books on shelf A is five times that of the remaining books on shelf B; If you take five books from shelf A and put them on shelf B, there are three times as many books on shelf A as on shelf B. How many books are there in Shelf A and Shelf B respectively?
3. There are three kinds of goods, A, B and C. If you buy 3 pieces of A and 7 pieces of B, 1 piece of C, * * * needs 300 yuan; If you buy 4 pieces of A, 10 pieces of B, 1 piece of C, * * * needs 400 yuan; Now I need to buy a, b and c, how much does it cost?
4. Teacher Liang bought a cross-stitch suit for the labor skill competition, and the price was 6 yuan. Considering the needs of customers, the cross-stitch shop has launched a membership card (the cardholder can use it for one year from the date of purchase); For each set of 30 yuan, buy a set of cross-stitch suits with cards, and each set of 3.5 yuan.
(1) If you can only choose one purchase method, and you plan to spend 100 yuan a year on cross stitch, please find out the purchase method that can maximize the number of purchase sets through calculation.
(2) How many sets of cross-stitch should I buy at least one year, so it is cost-effective to buy a membership card?
A company urgently transports a batch of fruits that are difficult to store from A to B, and there are three modes of transportation to choose from: car, train and plane. As we all know, the distances traveled by cars, trains and planes are 3S km, 2S km and s km (s >: 50) respectively. The main reference data of the three modes of transportation are shown in the following table. If the loss of this batch of fruit during transportation (including loading and unloading time) is 300 yuan/hour.
(1) Write the relationship between the cost y of various vehicles and the transportation distance.
(2) What kind of transportation is better? It is agreed that it is best to minimize the sum of expenses and losses in transportation.
Main reference data sheets of three modes of transportation
Transportation speed (km/h) Transportation cost (yuan/km) Loading and unloading time (hours) Loading and unloading cost (yuan)
Automobile 50 8 2 1000
Train 100 4 4 2000
Aircraft 400 16 2 1000
6. In order to welcome the National Day, the workers raised 100 balloons in Tianfu Square. Xiao Ming counted and said, "If you look at it the other way around, there are three red ones in every four." Xiaohua said, "Conversely, three of the four are yellow." They are right. Can you figure out how many red balloons and how many yellow balloons there are? 7. During the Chinese New Year, grandpa had a certain amount of RMB and gave it to Xiaoming, Xiaohong and Xiaogang as lucky money. Grandpa plans to give Xiaoming, Xiaohong and Xiaogang lucky money 1/3, 1/4 and 1/6 respectively. As a result, grandpa's money was only 75 yuan. How much money did grandpa have before? 8. When a store sells a China color TV at a 20% discount, it can still make a profit of 20% (20% of the purchase price). It is understood that the purchase price of this brand of color TV is 2000 yuan. What's the price of this brand of color TV? 9. From 1 999165438+1October1,the national savings deposits are subject to interest tax at a rate of 20%. On May 1999 1 day, Mr. Wang deposited RMB 20,000 in the bank for one year with an annual interest rate of 3.77. The annual interest rates of 10 and 1 year, 2-year, 3-year and 5-year savings are 2.25%, 2.43%, 2.70% and 2.88% respectively. Calculate the principal of 1000 yuan to participate in these four kinds of savings respectively, and what is the interest earned at maturity (state regulations; Personal savings are subject to interest tax from 1 999165438+10/month1,and the interest tax rate is 20% of the interest. What can you find from the analysis? (Hint: Interest = principal, annual interest rate, saving years)