The following questions will be answered a few times, which is the more difficult question in the ju

1.Let the speed of A be x, the speed of B be y and the height of the mountain is h

2=（h/x）+400/

2 + (400 h) = h x + (then do the math yourself.)

Hee-hee, I copied it, it's so tiring to type}

2.If the cost is 2x, then the profit is x

2x+x)*75%=9x 4 Total sales: 2x+x*70%=27x 10 discounted: 27x 1o-9x 4=9x 20 If not discounted: (2x+x)*25%=3x 4 So let the reduction be a, then:

3x/4*a=9x/20

Solution: a=60%.

3.You can calculate the denominator first and then find the regularity to simplify:

1=n1/3+2/3+3/3=2...2n-1=2=>2=n1+2+3+4+5)/5=3...2n-1=5=>3=n1+2+3+4+5+6+7)28/7=4...

2n-1=7=>4=ns=[1+1+2(n-1)]*n/2<=2006,n^2<=2006<=45

When n=44, an=1+(44-1)*2=87s=(1+87)*44 2=1936

n=45,2*45-1=89,1/89,2/89,..

89 is the 70th place in this group, that is, 70 89

Hehe, typing is tiring, hope.

1. Let the speed of A be x, the speed of B be y, and the mountain height is h

2=（h/x）+400/

2+（400/h）=h/x+（

It's okay to solve it, my level is limited.

1. Let the speed of A be x, the speed of B be y, and the mountain height is h

2=（h/x）+400/

2+（400/h）=h/x+（

1. The first digit on the left of a six-digit number is 1, if you move this number 1 to the far right, then the resulting six-digit number is 3 times the original number. Find the original number.

2. The sum of the three numbers of A, B and C is 255, and it is known that the number A is divided by the number B, and the number B is divided by the number C is the quotient 5 and more than 1What are the three numbers A, B, and C.

3. There is a highway from City A to City B, which is divided into three sections. On the first stage, the speed of the car is 40 kilometers per hour, on the second stage, the speed of the car is 90 kilometers per hour, and on the third stage, the speed of the car is 50 kilometers per hour. It is known that the first section of the road is exactly twice as long as the third section.

At present, two cars depart from A and B at the same time, go in opposite directions, and after 1 hour and 20 minutes, they meet at 1 3 places in the second section (1 3 places from A to B direction). Q: How many kilometers are A and B apart?

4. When the two puppies have just finished walking the iron bridge length 1 3, a train comes from behind, and a dog runs backwards and runs to the bridgehead B, and the train just arrives at B; The other dog ran forward, and when he ran to the bridge A, the train also ran to A, and the speed of the two puppies was 6 meters per second, and asked what was the speed of the train?

5. Xiao Ming walked from the top to the bottom along the escalator that moved upward, he walked 150 steps, and his classmate Xiao Gang walked along the escalator from the bottom to the top and walked 75 steps, if Xiao Ming walked 3 times faster than Xiao Gang, then what is the number of steps of the escalator that can be seen?

6. If a car drives from A to B, if the speed is increased by 20, it can arrive one hour earlier than the original time; If you drive 120 kilometers at the original speed and then increase the original speed by 25, you can arrive 40 minutes in advance.

7. A dog chases a rabbit, the dog jumps 6 times, the rabbit can only jump 5 times, the distance of the dog jumps 4 times and the distance of the rabbit jumps 7 times is the same, the rabbit runs for a kilometer after the dog begins to chase behind, and the rabbit runs how far to be caught up by the dog.

8. Three animals race, the speed of the fox is 4 5 of the rabbit, the speed of the rabbit is 2 times that of the squirrel, the squirrel runs 12 meters less than the fox in one minute, ask: how many meters more does the rabbit run than the fox in half a minute?

9. A and B set off at the same time, in the same place and in the same direction on the 210 km long ring road at a speed of 160 kilometers and 20 kilometers per hour respectively. Whenever car A catches up with car B, car A slows down by 1 3 and car B increases by 1 3Q:

How many kilometers did the two cars travel when they were just the same speed?

10. A and B are 125 kilometers apart, and A and B ride bicycles from A and B at the same time and walk in opposite directions. C rides a motorcycle at 63 kilometers per hour. If A's speed is 9 kilometers per hour, and when C arrives at A for the second time (the time when A and C depart at the same time is C's 0th return to A), A and B are 45 kilometers apart, ask:

When C returns to A for the fourth time, how many meters is A and B apart?

1 432-234=198 987-789=198 654-456=198, look closely at what are the rules of these three equations, can you write a few more equations like this? （543 ）－345 ）=198 （ 321 ）－123 ）=198 （ 876 ）－678 ）=198

2 The sum in the equation each represents a number, known ( then =( )=( ).

3 One day, there were 117 attendees and 3 absences in the sixth grade, and the absenteeism rate was ( ) the next day attendance was ( ) and the next day ( 111 ) attendance.

4. The speed of car A is 120% of that of car B, and car A is (20)% faster than car B

5 In the division equation ( )36=12......(, the remainder is maximum (35), and the dividend is (467).

6,300 kg of paddy was processed to yield 225 kg of rice. The yield of this paddy is (75)%.

1 for the first time.

2 for the second time.

The third time 4 pcs.

8 for the fourth time.

The fifth 16.

6th 32 pcs.

64 for the seventh time.

The equivalent general term is an=a1x2 (n-1).

Summing sn>=120, n=7 is the minimum.

So play for at least seven minutes.

Hopefully!

The first encounter was 60 kilometers from land rent, indicating that the first car traveled a total of 60 kilometers. The second encounter with car A traveled 60 * 2 = 120 kilometers, a total of 120 + 60 = 180 kilometers, which can be 30 kilometers away from place B, indicating that the distance between the two places is 180-30 = 150 kilometers, which summarizes the early omen process.

150 km.

A: AB The distance between the two places is 150 kilometers.

Give the best thank you.

1 15951 16061 16161 16161-15951=210/3=70

2. A is 1000 meters faster than B, 4 minutes per hour is the total time required for two people to run a lap, set an unknown number x is the speed of B, x +1000 1h is the speed of A, 4 minutes is 1/15th of an hour.

The velocity is added and multiplied by time equal to 1000 meters, which gives the value of the unknown.

1. According to the actual situation, the following should be 16061 and 16261, so the speed of this car is (16161-15951—) 3=70 kilometers.

2. The sum of the speed of A and B is 1000 4 = 250 meters.

The speed difference is 1000 60 = 50 3 meters.

So the velocity of A is (250+50 3) 2=400 3 meters, and the velocity of B is 250-400 3=350 3 meters.

1.The middle time was 16061, this time it was 16161. So (16161-15951) 3=110 3

3600(x-y)=1000