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Urgent problem solving in fourth grade mathematics (answer).
1. The school auditorium has 28 seats in each row, and the fourth grade 180 students. How many lines can you fill in? How many people are left?

A car travels 80 kilometers per hour, and the speed of the express train is twice that of this car. Maglev trains travel 20 kilometers more per hour than express trains. Please ask two questions and answer them according to the conditions.

3. The school carried out water-saving activities, saving 435 tons of water in the first three months. According to this calculation, how many tons of water can the school save a year?

The price of basketball in a shop is one 90 yuan. On New Year's Day, a promotion activity of "buy ten and get one free" will be held, that is, every purchase of 10 will be given 1 0, and the shortage of 10 will not be given. If Miss Li wants to buy 25 [including gifts], how much will it cost?

Teacher Jiang led the young pioneers to buy fruit for the nursing home. A: per box 18kg, * * 108 yuan, b: per box 12kg, * * 84 yuan.

What fruit is cheaper to buy?

[2] How much does it cost for Teacher Jiang to buy 36 Jin of fruit?

6. Sweet and her parents, grandparents traveled abroad during the "Eleventh" holiday. One-way ticket price is 48 yuan per person, and children's tickets are half price.

How much is the round-trip fare for the Tian Tian family to travel?

[2] Stay at the destination for 3 days, and pay for accommodation in 59 yuan. If Tian Tian wants to stay for another two days, how much will it cost?

Short answer: 1: 180 divided by 28 equals 6+ 12, so you can fill in 6 lines, leaving 12 people;

2. Question 1: What is the speed? (Answer: Speed 2 times 80 equals 160 km/h)

Question 2: What is the speed of the express train? Answer: the speed of the express train is equal to 160 times 3 plus 20 equals 500 kilometers per hour.

3. The school can save 435 times 4 a year, which is equal to 1740 tons.

4.25 There are two 10, that is to say, two were given when buying, so the teacher needs to buy 23, so the total * * * needs 23 times 90, which is equal to 1980 yuan.

5.( 1) 108 divided by 18 is equal to 6, that is to say, 6 yuan is per kilogram for Class A fruits, while 84 divided by 12 for Class B fruits is equal to 7 yuan, so Class A fruits are cheap.

(2) At least 36 times 6 equals 2 16 yuan.

6.( 1) The Sweet Family has four adults and one child, so the round-trip fare is (48 times 4 plus 24 yuan, which is equal to 2 16 yuan) times 2, which is equal to 432 yuan.

(2)59 divided by 3 and multiplied by 2 is approximately equal to 40 yuan.