Solution: suppose there are x nickels and y nickels.
X+Y=30 ( 1)
2X+5Y=99 (2)
Y = 30-x (3) from ( 1)
Replace (3) with (2)
2X+5(30-X)=99
3X=5 1
X= 17
Substitute X= 17 into (1) to get Y= 13.
Answer: There are 17 nickels and 13 nickels.
(2) The school bought three volleyballs and two footballs, which cost11yuan. Each football is more expensive than each volleyball, 3 yuan. How much is each volleyball and football?
( 1 1 1-6)÷5=2 1
2 1+3=24
(3) Kindergarten * * * three classes are divided into 270 apples, with the big class being more than the middle class 10 and the small class being less than the big class 14. How many apples are divided into three categories?
3. solution: suppose that the category is divided into x apples, then according to the meaning of the question.
X+X- 10+X- 14=270
X=98
So the three classes are divided into 98, 88 and 84 apples respectively.
There are *** 100 chickens and rabbits, with a total of 344 feet. How many chickens and rabbits are there?
There are 39 cars parked on the playground, including tricycles and bicycles. There are 96 wheels, so how many tricycles and bicycles are there?
6. There is a folk song: "A hunter, a team of dogs, two walking side by side, counting 300 heads and 800 feet." How many cats and dogs are there?
7. Forty-four students went boating. They rented nine boats. There are 6 people in the big boat and 4 people in the small boat, which is just full. How many ships did they rent?
8. 20 math problems, 8 points for doing one right and 4 points for doing one wrong. Lily did every question and got 100. How many questions did she make wrong?
4. Assuming that 65,438+000 rabbits are rabbits, there will be 4× 65,438+000 = 400 feet, so there will be 400-344=56 feet, and a chicken will have 4-2=2 feet, so the chicken will have 56÷2=28 rabbits with 65 feet.
5. Assuming that all 39 vehicles are tricycles, there will be 39×3= 1 17 wheels, and then there will be 1 17-96=2 1 wheels. A bicycle will have 3-2= 1 wheels according to the tricycle, so the bicycle has 265438+.
6. Assuming that all 300 dogs are dogs, there are 4×300= 1200 feet. So 1200-880=320 feet, and one person has 4-2=2 feet, so there are 320 people and 3000 dogs.
7. Assuming that all 9 ships are large, they can take 6×9=54 people, so 54-44= 10 people can take more. A small boat can take 6-4=2 people, so there are 10÷2=5 large ships and 9-5=4 ships.
8. Assuming that everything Xiaoli does is right, she will get a score of 20×8= 160. Xiao Li only got 100, so Xiao Li lost 160- 100=60. If she does a wrong question, she won't get 8 points, but will be deducted 4 points, so she loses 8+4 = 65440.
9: Three bugs * * * have 18. They have 20 pairs of wings and 1 16 legs. Among them, each spider has 8 legs without wings, each dragonfly has 2 pairs of wings and 6 legs, and Zen has 1 pair of wings and 6 legs. How many are these three kinds of insects?
9. First of all, assuming all dragonflies, there should be 18*6= 108 legs, but there are actually 1 18 legs, which is less than the actual number 10. It's because one spider is missing two, which means the number of spiders is 10/2.
Then the number of dragonflies and cicadas is 18-5= 13. Assuming that they are all cicadas, they should have 13 pairs of wings. In fact, there are 20 pairs, and 7 pairs are missing. Because one dragonfly is missing, the number of dragonflies is 7/ 1=7, leaving 65433.
Namely: spider: 5, cicada: 6, dragonfly: 7.
Chicken and rabbit 10 * * * 100, with a total of 344 feet. How many chickens and rabbits are there?
1 1. There are 39 cars parked on the playground, including tricycles and bicycles. There are 96 wheels, so how many tricycles and bicycles are there?
12, there is a folk song: "A hunter, a team of dogs, two walking side by side, counting 300 heads and 800 feet." How many cats and dogs are there?
13, 44 students went boating, and they rented 9 boats. There are 6 people in the big boat and 4 people in the small boat, which is just full. How many ships did they rent?
14, 20 math problems, 8 points for doing one right, 4 points for doing one wrong, and Lili's score for each problem is 100. How many questions did she make wrong?
10, assuming that 100 rabbits are rabbits, there will be 4× 100=400 feet, 400-344=56 feet, and a chicken will have 4-2=2 feet, so the chicken will have 56 ÷ 2 = 26.
1 1, assuming that all 39 vehicles are tricycles, there are 39×3= 1 17 wheels, and there are 1 17-96=2 1 wheels.
12, assuming 300 dogs, there are 4×300= 1200 feet. In this way, you will get 1200-880=320 feet. According to the dog's feet, a person is 4-2=2, so there will be 320 ÷ 2 = 65438+.
13, assuming that all 9 ships are large and can take 6×9=54 people, then you can take 54-44= 10 people. Small boats can take 6-4=2 people, so there are 10÷2=5 large boats and 9-5=4 people.
14. Assuming that Xiao Li did everything right, she would get a score of 20×8= 160. Xiao Li only got 100, so Xiao Li lost 160- 100=60. If she does a wrong question, she won't get 8 points, but will be deducted 4 points, so if she does a wrong question, she will lose 8 points.
Profit and loss problem: 1. Measure the depth of the well with a rope. If the rope is folded twice, it will be 5 meters more. The rope is missing 4 meters after being folded three times. How long is the rope? How deep is this well?
1/2 of the rope is greater than1/3 (5+4) = 9m, so the rope is 54m long.
Well depth =54× 1/2-5=22 meters.
Daxiong left home for school at 7: 20 in the morning. If he walks 50 steps per minute, there will be seven minutes before class time when he gets to school. If he walks 35 steps per minute, he will be five minutes late and ask for school time.
The reason why you need to walk more is that you walk less every minute 15 steps.
420/ 15=28 It takes 28 minutes to reach more than 420 steps, because the difference is 7 minutes.
7+28=35 (minutes) is the required time.
3: There is a basket of apples and a basket of pears. If you eat an apple and two pears every day, there will be three apples left when the pears are finished; If you eat two apples and three pears every day, there will be five pears left when the apples are finished. Do you know how many apples there are? How many pears are there?
Eat 1 apple and 2 pears every day. If you want to eat all the apples, you need 3×2=6 pears.
So if you eat 2 apples and 4 pears every day, you need 6 pears if you want to eat all the apples.
Actually eat 2 apples, 3 pears and 5 pears every day.
Pear is 6+5= 1 1.
Because I eat less 4-3= 1 every day.
Therefore, if you eat two apples a day, you will eat (6+5)÷(4-3)= 1 1 day.
There are 2× 1 1=22 apples.
3× 1 1+5=38 pears.
In a general cleaning, the teacher assigned several people to clean the glass. If two of them wipe 4 pieces each and the others wipe 5 pieces each, there are 22 pieces left. If you wipe 7 yuan each, it's over. Find out the number of glasses and the number of people cleaning them. ：
If two of them clean four pieces of glass and the rest each clean five pieces of glass, then the remaining 22 pieces are regarded as "If each person cleans five pieces of glass, then the remaining 22 pieces are: 22-2*(5-4)=20 pieces of glass.
Then use profit and loss problem to solve:
20/7-5 = 10 people
7* 10=70 yuan
A: There are 10 people cleaning the glass. There are 70 pieces of glass.