A and B two cars from a and B at the same time, the speed ratio is 4:5, after meeting the two cars continue to move forward, respectively, after arriving at Ba two places immediately return They meet again on the way. If they meet 40 kilometers apart, how many kilometers are AB and ab?

A and B two cars from a and B at the same time, the speed ratio is 4:5, after meeting the two cars continue to move forward, respectively, after arriving at Ba two places immediately return They meet again on the way. If they meet 40 kilometers apart, how many kilometers are AB and ab?

(40 / 2) (5 + 4) / (5-4) = 180 km
180km
If the total amount of work is fixed, is the completed part in inverse proportion to the remaining part? Explain the reasons
The total amount of work is fixed, and the completed part is not inversely proportional to the remaining part
Because the total amount of work = completed part + remaining part
There is no proportional relationship
When the total amount of work is fixed, the completed part is not inversely proportional to the remaining part,
Because the product of the completed part and the remaining part is not certain.
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There are 160 tons of coal in two piles, 2 / 5 more than 20 tons transported by Party A and 2 / 5 less than 6 tons transported by Party B
160 * 2 / 5 + 20-6 = 78 tons
Conditions are not enough. There are two answers
A and B run from a and B at the same time. They meet 40 minutes later. After meeting, they continue to move forward at the same speed. B reaches the midpoint between a and B in 5 minutes. It takes a total of 5 minutes for a to complete the whole journey______ Minutes
A: it takes 72 minutes for car a to complete the whole journey
A gas station can only refuel one car at a time. There are trucks, vans, cars, motorcycles, and each one comes to the gas station at the same time. It takes seven minutes to fill up a big truck, four minutes for a small truck, four minutes for a car, and two minutes for a motorcycle. The gas station should reasonably arrange the refuelling sequence of the four cars, To minimize the total time (including the time for refueling and queuing), the shortest time is ()
A.18 A.26 C.37 D.48
It takes four minutes to get the pickup,
i 'm sorry
The answer could be b.26 or c.37
Motorcycle 2
Car 2 + 4 = 6
Pickup truck 2 + 4 + 5 = 11
Big truck 2 + 4 + 5 + 7 = 18
The total is: 2 + 6 + 11 + 18 = 37
Eighteen
Two piles of 160 tons of coal, pile a transported more than 2 / 5 of 20 tons, pile B transported less than 2 / 5 of 6 tons, how many tons were transported?
Total transportation: 160 * (2 / 5 + 2 / 5) + 20-6 = 142 tons
A and B start from a and B at the same time, and travel in opposite directions. The speed ratio is 4:5. When they meet, the distance ratio is (): ()
Seeking ideas - A-
I'm dependent on you,
Train of thought: meet time is fixed, speed ratio is equal to distance ratio
So: car a and car B start from a and B at the same time and travel in opposite directions. The speed ratio is 4:5. When they meet, the distance ratio of the two cars is (4): (5)
When a and B start from a and B at the same time, they travel in opposite directions. The speed ratio is 4:5. When they meet, the distance ratio is (4): (5)
Let the time from starting to meeting be t. the speed of a is 4V and that of B is 5V.
Then the distance s a of a = 4vt,,,, the distance S B of B = 5vt
So s a: S B = 4:5
The key to solve the problem is that the two cars take the same amount of time.
Wrong. It should be 5-4. We've done it. We've criticized it
The number ratio of cars and vans sold in a 4S store in September was 3:5. There were 160 cars of these two kinds, each with its own number
Car
160 ± (3 + 5) X3 = 160 ± 8x3 = 60 vehicles
Van
160-60 = 100 vehicles
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There are two piles of coal, pile a has 4.5 tons, pile B has 6 tons, pile a uses 0.36 tons a day, pile B uses 0.51 tons a day. After a few days, the remaining tons of the two piles are equal?
Let the remaining tons of the two piles be equal after X days. According to the meaning of the question, we get: 4.5-0.36x = 6-0.51x, 0.51x-0.36x = 6-4.5, & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; 0.15x = 1.5, & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; X = 10
A and B start from a and B and run in opposite directions. When they start, the speed ratio of a and B is 5:4. After they meet, when a arrives at B, B is 15 kilometers away from A. then how many kilometers are there between a and B?
A——D————C—————B
As shown in the figure, it takes x hours for Party A and Party B to meet at point C, so AC = V A * x, BC = v b * x, and then Party A and Party B respectively drive for y hours, BC = V A * y, CD = v b * y. this problem is to sort out a series of proportional relations, and express the set unknowns in known form. AC = V A * x, BC = v b * x is also equal to 1.2V a * y (because party a accelerates by 20%), CD = 1.25V b * y (because Party B accelerates by 25%), Through the BC segment length as the intermediary, we can get v b * x = 1.2V a * y, and we know that the speed ratio of a and B is 5:4, so we can get x = 1.5y. The only thing related to the specific value is that the length of ad segment is 15km, which is the distance between B and point a after driving x + y hours. However, through the segment diagram, we can know that AC segment is the distance between a and point a after driving x hours. Taking AC segment as the intermediary, we can get 15 + 1.25V b * y = V A * x, according to V A: v b = 5:4, Using V A = 1.25V B and x = 1.5y, substituting the two conditions, we get V A * y = 30, BC section is 1.2V a * y, so BC = 30 * 1.2 = 36, CD = 1.25V b * y = V A * y = 30, total distance AB = AD + CD + BC = 15 + 30 + 36 = 81 (km)