The ratio of walking speed between a and B is 7:5. A and B start from a and B at the same time. If they walk in opposite directions, they will meet in 0.5 hours. If they walk in the same direction, then a needs to catch up with B______ Hours

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• 1. The weight ratio of a and B is 8:5. Take 20 kg out of a basket and put it into B basket. At this time, B basket apples are 4 kg more than a basket apples. How many kg do the two baskets weigh?
• 2. If a car increases its speed by 20% from place a to place B, it will arrive ahead of time. If it runs at the original speed of 100 km and then increases its speed by 30%, it will be just right How many kilometers is the distance between a and B? Set an unknown number to write out the process of solving the equation
• 3. A car drove from city a to city B at a speed of 40 kilometers per hour. After three hours of driving, due to rain, the speed was reduced by 10 kilometers, 45 minutes later than the expected time. It is necessary to find the distance between city a and city B
• 4. When the plane is launched between the two cities, it takes 4H to follow the wind and 5h to return against the wind. The speed of the plane in the calm wind is 360km / h, so it is necessary to calculate the speed Wind speed and distance between two cities
• 5. The two cars run from east to west at the same time. A travels 56 kilometers per hour, B 48 kilometers per hour. The two cars meet at 40 kilometers from the midpoint, east to west How many kilometers are there between the two places?
• 6. In November, a cement plant plans to produce 2400 tons of cement. What percentage of the planned production has been completed? What percentage of the production has been increased?
• 7. There are 48 boys and 36 girls in Grade 1. The number of boys and girls in each row should be the same. How many people are there at most in each row? How many rows are there for men and women? Write clearly
• 8. The number of female workers in a workshop is 60% of that of male workers 1. What is the ratio of female workers to male workers? 2. What is the ratio of the number of female workers to the total number of workers in the workshop? 3. What is the ratio of the number of male workers to the total number of workers in the workshop? 4. What is the ratio of male workers to female workers?
• 9. Among the students reading in the reading room, there were 10 more boys than girls. Later, the number of boys decreased by a quarter and that of girls by a sixth The remaining number of boys and girls is the same, the original total of more people to read
• 10. It is known that the ratio of the three numbers of a, B and C is 3:4:5. The number of a is 16 less than that of C. what is the number of B and C
• 11. There are some goods on the truck. After loading two packages of 2.5 tons, they are 1.6 tons lighter than the carrying capacity, and the carrying capacity is 10 tons How many tons of freight cars are there
• 12. There are two piles of cement. If 15 tons are transported from pile B to pile a, this is pile a, which is 6 / 5 of pile B. pile a used to be 45 tons, but how many tons did pile B have?
• 13. Party A and Party B start from ab at different speeds at the same time and travel in opposite directions. They meet on the way. The meeting point is 60 meters away from A. after meeting, the two vehicles continue to travel in the same direction Go forward, return immediately after reaching the destination, and meet again on the way. The meeting point is 40 meters away from city A. how many meters away is the meeting point from city B at the first meeting?
• 14. A car travels 156 kilometers three hours before it goes from a to B. according to this calculation, it takes eight hours to go from a to B. how many meters is the distance between a and B
• 15. The two cars run from two places 324km apart at the same time. Two hours later, they meet on the way. It is known that the speed ratio of car a and car B is 3:2
• 16. A and B leave AB at the same time and meet 45 km away from the midpoint. It is known that a's speed is 1.5 times that of B's. how many km is the distance between AB and B
• 17. How to calculate the symmetry axis X = - B / 2a of quadratic function
• 18. The symmetry axis of quadratic function f (x + a) = f (b-X) is x = (a + b) / 2. Please give a detailed explanation,
• 19. Given that a quadratic function has f (2 + T) = f (2-T) for any real number T, how to prove that its axis of symmetry is x = 2 Given the function f (x) = X2 (the square of x) + BX + C, for any real number T, f (2 + T) = f (2-T), how to prove that the symmetry axis of this quadratic function is x = 2?
• 20. The quadratic function f (x) satisfies f (2 + x) = f (2-x). Why does it explain that the axis of symmetry is x = 2