Give me a practical problem about fractional equations. Hurry, hurry! Thank you

2008, Zaozhuang) a project, in the project bidding, received a bid, B two engineering team bidding, construction day, need to pay a project team project 10,000 yuan, B engineering team project 10,000 yuan, the project leading group according to the bidding of A, B two teams of bidding, there are the following schemes:

1.Team A completed the project on its own, just as scheduled;

2.Team B completed the project alone by one day more than the allotted date.

3.If Team A and Team B work together for 3 days, the rest of the work will be completed on schedule by Team B alone.

Let's ask: On the premise of not delaying the construction period, which construction plan do you think is the most economical for the project? Please explain why.

2008, Yibin) A and B are 360 kilometers apart, with the transport convoy from A to B, when 150 kilometers away, received a notice, asked to arrive in advance, the team decided to increase the speed to the original times, arrived at B for 6 hours, asked what was the original speed of the convoy?

A small boat from port A to port B downstream needs to travel 6h, from port B to port A against the current needs to travel 8h, one day the boat from port A to port B at 6 o'clock in the morning when the boat departed from port A to port B, found a lifebuoy on the way to the water, after receiving the notice immediately returned, 1h later found the lifebuoy, question (1) if the boat according to the speed of the current from port A to port B how many hours it takes? (2) When did the lifebuoy fall into the water?

Explanation: (1) Set the purchase price of each pencil for the first time is $x.

600/x－30＝600/（5/4x）

Solution: x=4

For the first time, the purchase price of each pencil was 4 yuan.

2) First purchase: 600 4 = 150 (branches).

The second purchase: 600 (4 5 4) = 120 (branches) set up Zheng stool to learn a yuan per pencil.

150 (A-4) + 120 (A-4 5 4) 420 solution: A 6

At least $6 per pencil.

Fractional application problem solving ideas: "--- review --- columns--- six steps to solve --- test --- answer".

1. Examination of the question - the actual situation described by the topic; a. Events and problems b. Relationship between numbers and --- (a. Use formulas; b. Use the actual situation of addition, subtraction, multiplication and division).

2. Set the corresponding unknowns; Note: The unit is unified, in order for the next equation to be meaningful3, the column equation; Note: It only makes sense to write the numbers after the units are unified into the equation 4. Solve the equation; Note:

The solution of an equation in mathematics is --- numbers, and the units are not written after it. Because there are already units in the location of the unknown.

5. Double inspection; a, whether it is the root of the fractional equation b, whether it conforms to reality 6, answer.

Hello, now multiply the denominator on both sides of the equation at the same time, remove the denominator, and then move the unknown to the left of the equation (the right side is also OK, depending on the habit, it is generally moved to the left), and then the next is to solve the unary equation. Then bring the solution of the equation back to the equation test (the purpose is, 1, bring x in to see if the denominator is 0, because the denominator can't be, to see if the equation is equal).

A's typing per hour is x B's typing per hour, y9000 x=7200 y, x+y=5400 x=3000, y=2400

Solution: If the enemy's speed is x kilometers per hour, the speed of our troops will be kilometers per hour (24 x) -48 60 = 30

Solution: x=5Answer: The speed of our troops is kilometers per hour.

If the speed of our troops is x, then the speed of the enemy troops is x

30/x+48/60=24/(x/

x = kilometers per hour.

The speed of our troops is x kilometers per minute.

The enemy's velocity is x km/h.

30/x+48=24/(x/

30/x +48 =36/x

30+48x=36

48x=6x=1 8= km.

The speed of our troops is 125 meters per minute.

If the first commodity is worth x yuan per kilogram, then the second is x + 300 yuan 900 x = 1500 (x + 300).

900(x+300)=1500x

600x=270000

x=450 yuan.

x+300=750 yuan.

The first commodity is worth 450 yuan per kilogram, and the second commodity is worth 750 yuan per kilogram.

1500-900=600

600 300 = 2, so there are 2 kilograms in total.

900 2 = 450 yuan.

1500 2=750 yuan.

So the two commodities are 450 yuan and 750 yuan per kilogram respectively.

Weight x per kilogram of the first type y y per kilogram of the second type y + 300xy = 900

x（y+300）=1500

x=2 y=450

The first type is 450 per kilogram and the second type is 750

Set the weight to x

So 1500 x-900 x = 300

x=2, so the first one is 450 yuan per kilogram.

The second is 750 yuan per kilogram.

Let the first commodity be x yuan per kilogram, then the second commodity is x + 300 yuan per kilogram, and the equation can be solved: 900 x = 1500 (x + 300) to get x = 450

The first commodity is 450 yuan per kilogram, and the second commodity is 750 yuan per kilogram.

1500-900=600

Let the first commodity be an x circle.

900+1500=2×（x+x+300）

Let's take two commodities as x kilograms.

then 900 x + 300 = 1500 x900+300x=1500

x = 2 (kg).

900 2 = 450 yuan per kilogram.

1500 2 = 750 yuan per kilogram.

The first batch of shirts purchased in the mall was x0,000 pieces, which was derived from the title.

8/x = - 4

Solve x =

Therefore, the first batch of shirts purchased in the mall was 2,000 pieces, and the second batch of shirts was purchased 4,000 pieces, and the total sales volume was (2,000 + 4,000-150) *58 + 150 * 58 * = 346,260 yuan.

So in these two businesses, the mall made a total profit of 346,260 - 80,000 - 176,000 = 90,260 yuan.

10,000 = 2,000 yuan, the title says that the purchase quantity is 2 times the amount of the first purchase, so it should be 4,000

If the passenger car takes time x from the highway from place A to place B, then the time required by the ordinary highway from place B to place A is 2x

then there is 480 x = 600 2x + 45

960/2x-600/2x=45

360/2x=45

2x=8x=4

Normal speed x high speed x +45 B to A 2y minutes A to B y minutes 2xy = 600

x+45）y=480

y=4 x=75

The average speed of driving on highways is xkm h, and the average speed on ordinary roads is x-45km h

480/x=600/2(x-45)

Solution x=120

t=480/120=4

The bus takes 4 hours to get from A to B by expressway.