3 math problems 10 minutes 30 minutes

1.Let A and B be x kilometers apart, and they will meet at the same time. S A = X-12 = T * V A (1).

sB=12=t*vB(2).

It can be obtained from 6 hours after the first encounter, and then 6 kilometers away from place A.

The distance traveled by A is A = x-6 + 12 = 6 * v A (3) The distance traveled by B is B = x - 12 + 6 = 6 * v B (4) Then from 1, 2, 3, 4 can get x = 30 km, and then substitute 3, 4 to get v A and v B 2The distance from the school to the farm is x km.

x = A: The distance from the school to the farm is in kilometers.

3.Set the speed of A x the speed of B y

2*(x+y)=20

2*(x-y)=4

x=6y=4

ps: Big brother, this is an Olympiad problem, 1 and 2 have to use a binary equation.

1.A and B respectively in A and B along the same route at the same time in each other, 12 kilometers away from B after meeting and continuing forward, respectively to B and A immediately after returning, 6 hours from the first encounter, the two met again 6 kilometers away from A to find the distance between AB and the speed of A and B.

Solution: The first time they met, the two walked a whole course, and the first time to the second time, the two walked a total of 2 whole courses, which took 6 hours, so the first encounter took 3 hours. B walks 12 kilometers in three hours, so B walks 4 kilometers per hour.

By the time of the second encounter, B had walked a total of 1 full distance and 6 kilometers for nine hours, or 36 kilometers. So the whole journey = 30 km. Let A travel x kilometers per hour, then 3(x+4)=30, and the solution is x=6

A walks 6 kilometers per hour, B walks 4 kilometers per hour, and the whole journey is 30 kilometers.

2.Ordinary students move at a speed of 4 kilometers per hour from school to farm labor, and when they have completed 1 kilometer, a student is ordered to go back to school to pick up something, he returns to school at a speed of 5 kilometers per hour, and immediately catches up with the team at the same speed after taking his things, and catches up with the team at a distance of kilometers from the farm, asking for the distance from the school to the farm.

Solution: It took him x hours to catch up with the team. then (1 4+1 5+x) 4=5x. The solution is x=9 5. The distance to the farm is 5 (9 5)+

3.Two hours later, the two met on the way, and after meeting, A returned to place A, but B still advanced like place A, and when A returned to place A, B was still two kilometers away from place A, and the speed of A and B was found.

Solution: Because A and B travel a total of 20 kilometers in two hours, the sum of the speeds of A and B is 10 kilometers. If A x km is , then B (10-x) km is . then 2x-2=2(10-x)The solution gives x= then 10-x=

A is a kilometer and B is a kilometer.

1.Untie; If $2 has x sheets, then $5 has 68-6-8-x=54-x sheets.

2×x+5（54-x)=203-3-8

2x+270-5x=192

2x+270=5x+192

2x+78=5x

2 yuan x=26 5 yuan; 54-26=282.The speed of the ship in still water is x kilometers per hour.

Sail downstream (x+3) 5 3

Sail against the current (X-3) 2

x+3)×5/3 = x-3）×2

5/3x+5=2x-6

5/3x+11=2x

x=333.Production of jacket fabric x meters, trouser fabric 600-x meters.

The amount of tops produced is the same as the amount of pants.

2×（x/3)=3×[（600-x)/3]2x/3=1800-3x/3

2x=1800-3x

x=360。。。Clothes Pants 600-360 = 240 Total 240 2 = 120

n 3 is the fraction lz can not be understood,,Typing so many words.

I'm so tired that I chose my number, and the one on the trumpet was wrong, and lz gave me this number.

1.If $2 has x sheets, then $5 has 68-6-8-x=54-x sheets.

2*x+5*（54-x)=203-3-8

2.The speed of the ship in clean water is x kilometers per hour.

Sail downstream (x+3)* 3 5

Sail against the current (X-3) 2

3.Production of jacket fabric x meters, trouser fabric 600-x meters.

The amount of tops produced is the same as the amount of pants.

2*（x/3)=3*[（600-x)/3]

2 yuan: 26 pieces of booth 5 yuan: 28 pieces.

60 km apart is 33 km-h.

Solution: The Suilu section is set up to produce tops with x meters.

x 600-x

x=360600-360=240 (m) 360*2=240 (sets).

Yuan: 26 sheets 5 Yuan: 28 sheets.

2。The distance is 60 kilometers and the speed is 33 kilometers when digging a sedan car.

3。Solution: Set up x meters to produce tops.

x 600-x

x=360 pants: 600-360=240 (m) 360*2=240 (balance pants).

1.2 yuan to cover the defeat: 26 dry grandsons 5 yuan: 28 pieces.

2.The distance is 60 km, and the speed is 33 km

A and B run on a 400-meter-long circular simple number of smart tracks, if they run at the same time, they meet every 3 and 3/1 minute, and if they run in the opposite direction, they meet every 40 seconds.

(1) The title of this question lacks conditions, and both of them are wrong. A question is worth 5 points, 5 is a singular number, and 6 and 2 are even numbers.

2) Dissolution: The manuscript fee is X yuan.

4000-800) yuan.

420 yuan < 448 yuan, indicating that the manuscript fee obtained is less than 4000 yuan.

x-800)×

x=3800

A: The manuscript fee is 3,800 yuan.

3) Unraveling x acres of eggplant and 25-x acres of tomatoes.

17x+18（25-x）=440

17x-18x+450=440

x=10 Profit=10 2400+15 2600=63000

Solution: Let the speed be v, the road from Wangjiazhuang to Cuihu is x kilometers, according to the title, it takes 3 hours from Wangjiazhuang to Qingshan, and 5 hours from Wangjiazhuang to Xiushui.

Then there is: 3v+50=x

5v=x+70

Solution: x=230

The road from Wangjiazhuang to Cuihu is 230 kilometers.

Solution: If A sells x, then B sells 12200-x, which is derived from the title.

1+6%）x+（1-5%）（12200-x)=12250106%x+95%(12200-x)=12250106%x+11590-95%x=1225011%x=12250-11590

11%x=660

x=6000

B: 12200-6000 = 6200 (only) = 3100 (double) A: 6000 (only) = 3000 (double).

A: A sold 3,000 pairs, and B sold 3,100 pairs.

Solution: A, B sold x pairs of shoes last year.

From the meaning of the question (1+6%)x+(1-5%)x=12250, x=6094

A sold 6094 * (1 + 6%) = 6459 pairs.

B sold 6094 * (1-5%) = 5789 pairs.

Lack of conditions such as the difference in sales volume between this year and last year.

In which year did the total sales of the two shoes be 12,250 pairs?

Because if 3000 yuan is taxed at 14%, 3000 * 14 100 = 420 (yuan) should be paid, so Xiao Wang's manuscript fee before paying tax is 3000 + 800 = 3800 (yuan), and the manuscript fee after paying tax is 3800-420 = 3380 (yuan).

set, a total of x pieces of sugar. Since each person gets the same number of sugar cubes. Therefore, the equation can be obtained.

1+1 7 (x-1)=2+1 7 [x-1-(x-1) 7 -2] x=36 36 students in total 6=6 (people) Answer. There were 36 pieces of candy on the plate and there were 6 students.

Suppose that the speed of this bike is x kilometers per hour. Equation (2375-x)*(10 60)=20 60*(3+x) Solve x=23 Answer, the speed of a bicycle is 23 kilometers per hour. The landlord chooses me.

Solution: The manuscript fee is set to be RMB.

-800）x14%=420

3800 A: This manuscript fee is 3800 yuan.