To transport 29.5 tons of coal, transport it three times by a truck with a load of 4 tons, and transport the rest by a truck with a load of 2.5 tons. How many times will it take to complete? It takes x times to complete 29.5-3 * 4 = 2.5x17.5 = 2.5xx = 7. 2. The trapezoidal site covers an area of 90 square meters, with an upper bottom of 7 meters and a lower bottom of 1 1 meter. How high is it? Its height is x m x (7+11) = 90 * 218x =180x =10. Its height is 10 m3. A workshop plans to produce 5480 parts in April. It has been in production for 9 days, and 908 more are about to complete the production plan. How many pieces will be produced on average every day in these 9 days? In these nine days, the average daily output is X 9x+908=5408 9x=4500 x=500. During these nine days, an average of 500 were produced every day. 4. The two cars of Party A and Party B walked in opposite directions at the same time from two places 272km apart. After three hours, the distance between the two cars was still17km. A travels 45 kilometers per hour, and B travels how many kilometers per hour? B travel x kilometers per hour (45+x)+17 = 272 3 (45+x) = 255 45+x = 85 x = 40 b travel 40 kilometers per hour. 5. There are two classes in grade six in a school, and the average score of mathematics last semester is 85. There are 40 students in six classes (1) with an average score of 87. 1. There are 42 students in Class Six (2). What is the average score? The average score is 40 * 87.1+42x = 85 * 82 3484+42x = 6970 42x = 3486x = 83. 6. The school bought 10 boxes of chalk, used 250 boxes, and left 550 boxes. How many boxes are there in each box? On average, there are10x = 250+55010x = 800x = 80 cases per case. There are 200 students in Grade 7 and Grade 4. During extracurricular activities, 80 girls jumped rope. The boys are divided into five groups to play football. How many people are in each group? The average number of people in each group is 5x+80 = 200x = 160x = 32. The average number of people in each group is 32. 8. The canteen brought 150 kg of rice, which was 30 kg less than the flour. How many kilograms of flour does the canteen send? Flour in the canteen x kg 3x-30 =150 3x =180 x = 60 flour in the canteen 60 kg 9. There are 52 peach trees and 6 rows of pear trees in the orchard. There are 20 more pear trees than peach trees. How many pear trees are there in each row on average? There are x pear trees in each row, 6x-52=20 6x=72 x= 12. There are 12 pear trees in each row on average. The area of a triangular plot is 840 square meters, the bottom is 140 meters, and the height is how many meters? The height is x m140x = 840 * 2140x =1680x =12, and the height is 12m 1. Li Shifu bought 72m cloth and just made 20 adult clothes, 65438+. Adult dresses are 2.4 meters each, and how many meters are children's dresses? The fabric for children's wear is16x+20 * 2.4 = 7216x = 72-4816x = 24x =1.5. Mother was six times older than her daughter three years ago. My daughter is 30 = 6 (x-3) 6x-18 = 30 6x = 48 x = 8. Daughter is 8 years old. 13. How long will it take for a car traveling at 50 kilometers per hour to catch up with a car traveling at 40 kilometers per hour that left two hours ago? Need x time 50x=40x+80 10x=80 x=8 need 8 time 14. Xiaodong went to the fruit shop and bought 3 kilograms of apples and 2 kilograms of pears. * * He paid 15 yuan, 1 kg of apples is more expensive than 1 kg of pears in 0.5 yuan. How much are apples and pears per kilogram? Apple 3x+2 (x-0.5) =155x =16x = 3.2 Apple: 3.2 pear: 2.7 15. Two cars, A and B, start from A and B at the same time and face each other. A travels at a speed of 50 kilometers per hour, while B travels at a speed of 40 kilometers per hour. How many hours does it take for A to reach the midpoint? A reaches the midpoint in x hours 50x = 40 (x+1)10x = 40x = 4a reaches the midpoint in 4 hours 16. A and B leave from A and B at the same time, face to face, and meet in 2 hours. If A starts from place A and B goes in the same direction at the same time, then A will catch up with B after 4 hours. It is known that the speed of A is 15km/, and the speed of B is x2 (x+15)+4x = 602x+30+4x = 606x = 30x = 5b and 5 17. Two ropes with the same length, the first one was cut 15m, and the second one was 3m more than the remaining three times of the first one. How long are these two ropes? It turns out that the length of each of the two ropes is xm3 (x-15)+3 = x3x-45+3 = x2x = 42x = 21. Originally, the lengths of the two ropes were 2 1m and 18 respectively. A school bought seven basketballs and 10 football * * and paid 20 yuan. As we all know, the price of each basketball is equivalent to the price of three footballs. How much is basketball and football each? 7x+1 0x/3 = 248 21x+10x = 744 31x = 744x = 24 each basketball: 24 each football: 81,carrying a batch of goods. Now we rent three A-class cars and five B-class cars from this company. If we pay the freight per ton, 30 yuan asks the owner how much: A can load X tons, and B can load Y tons, so 2x+3y = 65,438+05.55x+6y = 35 gives x = 4 y = 2. Solution: increase x% (1-10%) * (1+x%) =1x% =1%to keep the total sales amount unchanged. Solution: Let the original price be X yuan (1-10%) X-40 = 0.5xx = 100 A: The original price is100 yuan. 4. There is 40 grams of salt water with 8% salt. How many grams of salt should be added to make the salt water contain 20% salt? Solution: Assuming that when X grams of salt is added, the pure salt is 40*8%, when X grams is added, it is 40*8%+x grams, and the brine concentration is 40+x grams, then (40 * 8%+X)/(40+X) = 20% (3.2+X)/(40+X) = A vendor bought a batch of eggs at a price of 0.24 yuan each, but accidentally broke 12 eggs in the process of selling, and the remaining eggs were sold at a price of 0.28 yuan each, making a profit of 1 1.2 yuan. How many eggs did the vendor buy? Solution: Suppose the vendor bought X eggs at first. According to the meaning of the question, the equation is listed as follows: (x-12) * 0.28-0.24x =11.28x-3.36-0.24x =11.20.04. There are 85 technicians in a workshop. On average, each person can process 15 pieces of A or 10 pieces of B every day, and two pieces of A and three pieces of B are matched with one set. How many people are arranged to process parts A and B respectively to make the parts A and B processed every day just match? Solution: Assuming that it takes X people to arrange production A, there will be (85-x) people to produce B. Because two A parts and three B parts are matched, the number of B parts multiplied by 3 can be equal to the number of B parts multiplied by 2:16 * x * 3 =10 * (85-x) * 2 Solution: x = 7. Hong Guang Electric Company can still make a profit of 20% by selling a certain color TV at 20% of the marked price. It is understood that the purchase price of this color TV is 1996 yuan. So what should the price of this color TV be? Solution: Set the list price to X yuan. 80% x = 1996×( 1+20%)80% x = 2395.2 x = 2994 8。 A store can make a profit of 20% by selling a commodity at 20% of the marked price. If the purchase price of this commodity is per piece in 22 yuan, what is the list price of each commodity? Solution: Set the price to X yuan. 80% x = 22×( 180m+20%)80% x = 26.4 x = 33 9。 On a section of double-track railway, two trains pass head-on. The speed of train A is 20m/s and that of train B is 24m/s. If the total length of train A is 65438+, the solution is: (180+160)/(20+24) = 7.28s/kloc-. Two students, A and B, walk in the same direction from two places five kilometers apart on the same road. A's speed is 5km/h, B's speed is 3 km/h, and a classmate is with a dog. It is known that the speed of the dog is 15km/h, and the total distance that the dog runs in this process is calculated. Solution: First of all, it must be made clear that the meeting time of Party A and Party B is equal to the running time of the dog, so the dog time = the meeting time of Party A and Party B = the total distance/the speed of Party A and Party B =5km/(5km/h+3km/h)=5/8h, so the dog distance = the dog time * the dog speed = 5/8h *15.

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