2. The school needs to make some signs, please ask Xiao Zhang and Xiao Li. It is known that it takes 4 days for Xiao Zhang to finish it alone, and 6 days for Xiao Li to finish it alone. After several days of cooperation, Xiao Zhang left because of something, and Xiao Li 1 day came again, and the two * * * retaliated against 450 yuan. If the remuneration is calculated according to the amount of work done by individuals, how should it be distributed? 1. Now a commodity is reduced in price 10% for promotion. In order to keep the total sales amount unchanged, how much is the sales volume increased over the original price?
Solution:1÷ (1-10%)-1
= 1/9
≈ 1 1. 1 1%
A: The increase is11.11%.
2. A said to B, "When I was your age, you were only 4 years old." B said to A, "When I reach your present age, you will be 6 1 year old." What are the ages of A and B now?
Solution: Suppose A is now X years old and B is now Y years old.
According to the meaning of the question:
x-y=y-4，
x-y=6 1-x
Solution: x=42, y=23.
A: A is 42 years old and B is 23 years old.
3. There are an odd number of cups with their mouths facing down, and it is called an action to rotate an even number of cups at the same time. Can you make all the cups face up after a few moves? Why?
No. Because the last cup is odd, of course, you can't do a sport.
4. If a batch of manuscripts has been copied for 30 hours, and B has been copied for 20 hours, it will be the remaining time for B to copy after 3 hours. B how many more hours do you need to copy? (column equation solution)
Setting b takes x hours.
1/30 * 3+X * 1/20 = 1
The solution is X= 18.
Party A and Party B ride motorcycles from AB, which is 60 kilometers apart, to a certain place. Party A is behind Party B. Party A rides 80 kilometers per hour and Party B rides 45 kilometers per hour. If A leaves 30 minutes earlier than B, how long will it take A to catch up with B?
1/2 * 80 = 40km
(60-40)/(80-45)=4/7
4/7+ 1/2= 15/ 14
Set x hours to catch up.
80X=45*(X- 1/2)+60
The solution is X= 15/ 14.
6. An airplane was originally scheduled to fly to its destination at a speed of 495 kilometers per hour, but due to the urgent task, its flight speed was increased to 660 kilometers per hour, and as a result, it arrived 1 hour earlier. What is the total flight distance?
x/495-x/660= 1
7. Eat 0.6 kg of soy sauce first, then eat the remaining 3/5, and there is 0.8 kg of soy sauce in the bottle. How many kilograms is this bottle of soy sauce?
(X-0 .6)*( 1-3/5)=0。 eight
8. A truck and a bus walk with their backs to each other at the same time. When the truck travels for 5 hours and the bus travels for 6 hours, the distance between the two cars is 568 kilometers. As we all know, trucks are 8 kilometers faster than buses every hour. How many kilometers does this bus travel per hour?
If the bus is X, the truck is X+8.
5(X+8)+6X=568
9. Xin Li was riding a bicycle, and Liu Qiang was riding a motorcycle. At the same time, he started from two places 60 kilometers apart and walked in opposite directions. After meeting on the road, move on and turn your back. Six hours after their departure, they were 240 kilometers apart. As we all know, the speed of Xin Li is18km. How many kilometers does Liu Qiang drive every hour?
6( 18+X)=60+240
10. Party A and Party B are 22.5km apart and walk in opposite directions at the speed of 2.5km/h and 5km/h respectively. At the same time, the puppy brought by Party A ran to Party B at a speed of 7.5km/h, and the puppy ran back to Party A immediately after meeting Party B, and ran to Party B again after meeting both parties ... until they met, seeking the distance the puppy had traveled.
Because the walking time of the puppy = the walking time of both parties.
So the distance of the puppy = the time of the puppy * the speed of the puppy.
= Time of Party A and Party B * Puppy speed
=22.5/(2.5+5)*7.5
=22.5 km
A car drives from A to B at a speed of 60 kilometers per hour. After driving for 4 hours and 30 minutes, the road was slippery in rainy days, and the car was not fast, and the speed was reduced by 20 kilometers per hour. The result arrived at B 45 minutes later than the expected time, so as to find out the distance between A and B (requirements: list two different equations).
(1) Assuming that the original estimated time is x hours and the distance between the two places is y kilometers, then:
60x = y；
60*4.5+(60-20)*(x-4.5+45/60)=y
The solution is x = 6 and y = 360.
(2) Assuming that the original estimated time is x hours, then:
60x = 60 * 4.5+(60-20)*(x-4.5+45/60)
The solution is x=6,
60x=360
(3) Assuming that the distance between the two places is y kilometers, then:
y/60+45/60 = 60 * 4.5+(y-60 * 4.5)/(60-20)
The answer is y=360.
Attendant: The distance between the two places is 360 kilometers.
Grade seven students go for a spring outing. If one bus is reduced, each bus will take 60 people. If one bus is added, each bus will take 45 people. How many students are there in the seventh grade? (Application problem of solving equations)
Suppose there are x people in the seventh grade.
Then there are 60 people in each car, x/60 cars in the car.
There are 45 people in each car, and x/45 cars are used.
Because there are two fewer cars for 60 people in each car than for 45 people in each car (the difference between subtracting one car and adding one car is two cars), make an equation.
x/60+2=x/45
x=360
A: There are 360 students in Grade 7.