Uncle Zhang went to the supermarket to buy 3kg of apples and 5kg of pears and paid 34.5 yuan. Aunt Li bought 1kg of apples and the same 1kg of pears and paid 9.5 yuan

Suppose that the apple is x yuan per kilogram and the pear is y yuan per kilogram
Then: 3x + 5Y = 34.5 ①
x+y=9②
① - 2 × 3 is 2Y = 7.5
y=3.75
Substituting y = 3.75 into 2 gives x = 5.25
Answer: Apple 5.25 yuan per kilogram, pear 3.75 yuan per kilogram

Aunt Li and Aunt Zhang go to buy fruit together. Aunt Li costs 28 yuan to buy 2kg apples and 3kg pears. Aunt Zhang costs 40 yuan to buy 2kg apples and 5kg pears. How much does it cost to buy 2kg apples and 5kg pears?

Set X yuan per kilogram for apples and Y yuan per kilogram for pears
There is a formula 2x + 3Y = 28
2X+5Y=40
From these two formulas, we deduce y = 6 and substitute y into Formula 1 to get x = 5
So Apple 5 yuan per kilogram, pear 6 yuan per kilogram

A natural number is a multiple of 4 and 5, including 1 and it has 9 divisors. What is the natural number?

The divisor of this number is odd, so it should be the square of a certain number, and because it is a multiple of 4 and 5, the square of 2 must be a multiple of 4, and the square of 5 must be a multiple of 5, so suppose that it is the square of 10, that is 100, and then let's look at its divisor, 1.2.4.5.10.20.25.50.100, which means that the number is 100

1. Write down all the basic events of the experiment. 2. The probability of the event "three people win or lose"

1. If the stone, scissors and cloth are respectively ABC, then the event a, B and C can be respectively:
AAA,AAB,AAC,ABA,ABB,ABC,ACA,ACB,ACC,
BAA,BAB,BAC,BBA,BBB,BBC,BCA,BCB,BCC,
CAA,CAB,CAC,CBA,CBB,CBC,CCA,CCB,CCC.
2. The odds are one in three

Use a 20 cm long and 15 cm wide rectangular sheet iron to make a 5 cm deep rectangular sheet iron box without cover (excluding the thickness of welding joint and sheet iron). What is the maximum volume of this sheet iron box?

As shown in the figure, the volume of the tin box: 5 × (20-5 × 2) × (15-5 × 2), = 5 × (20-10) × (15-10), = 5 × 10 × 5, = 250 (cm3). Answer: the maximum volume of the tin box is 250 cubic centimeters

One table can seat four people, two tables can seat six people, how many tables do you need to sit 80 people

Number of people = 2 × number of tables + 2
Number of tables = (80-2) △ 2 = 39

5.6 square meters () 56 square decimeters () 12 decimeters () 1 meter 20 cm 2.5 kg () 250 g 3 yuan 8 jiao () 3,70 yuan compare size

5.6 square meters (> 56 square decimeters, 12 decimeters (=) 1 meter, 20 cm, 2.5 kg (> 250 g), 3 yuan, 8 jiao (> 3,70 yuan)

The number ratio of story books to science and technology books in the book corner of a class was 1:8. Later, students bought five story books, so the number ratio of story books to science and technology books was 1:4. How many books were there in the book corner?

Science and technology books: 5 △ 14-18, = 5 △ 18, = 40 (Books); story books: 40 × 18 = 5 (Books), total books: 40 + 5 = 45 (Books); answer: there were 45 books in the book corner

Find the rule 2, 5, 9, 14, 20 what is the number 2008? What is the formula?
What is the solution formula?

Formula: (n & sup2; + 3n) △ 2
So just substitute n = 2008
As for the process, have you studied algebra in high school? It's very simple. I haven't touched this for a long time. I don't want to type in the specific derivation process. It's troublesome. Forgive me. Of course, if you need it very much, I can supply it to you
PS: watch on the first floor

Measuring the diameter of thin copper wire
A student wants to measure the diameter of a thin copper wire with length L. the experimental steps are as follows:
A. Straighten the thin copper wire and measure the length L1 of the thin copper wire with a scale;
B. Measure the total length L2 of the copper wire on the round pencil rod with a scale;
C. Divide the length of copper wire L1 by the number of turns of copper wire n to get the diameter of thin copper wire D;
D. The thin copper wire is tightly wound on the pencil rod;
E. Count the number of turns n of the thin copper wire wound on the pencil rod
(1) In the above steps, the unnecessary step is, the wrong step is, and the missing step is f
(2) The reasonable order of experimental steps should be

(1) In the above steps, there is no necessary step (A. straighten the thin copper wire and measure the length L1 of the thin copper wire with a scale)
The wrong step is (C. divide the length of copper wire L1 by the number of turns of copper wire n to get the diameter of thin copper wire d), and the missing step is (f) (divide the total length of copper wire winding L2 by the number of turns of copper wire n to get the diameter of thin copper wire d)
(2) The reasonable sequence of experimental steps should be (d-b-e-f)

Uncle Zhang went to the supermarket to buy 3kg of apples and 5kg of pears and paid 34.5 yuan. Aunt Li bought 1kg of apples and the same 1kg of pears and paid 9.5 yuan