20 points for elementary school math problems, 10 points for elementary school math problems, 30 poi

The orange was originally 24 kilograms, and the pear was originally 6 kilograms.

Because there are 2 kg left for pears, there are 2 2 = 4 kg left for oranges.

So the pears sold = the original pears - the remaining pears are 2 kilograms.

Because the number of oranges sold is 5 times that of pears, the number of oranges sold = 5 (original pears - 2) so the number of original oranges minus 4 = the number of oranges sold 5 (original pears - 2) and because oranges are 4 times that of pears, there are 24 kg of oranges and 6 kg of pears.

Actually, it's much easier to set the equation for oranges x and pears for y.

The remaining oranges are twice as large as the pears, and the pears are left with 2 kilograms. The remaining oranges are 2 2 = 4 kilograms, and if the pear turns out to be x kilograms, the oranges are 4 kilograms.

4x-4)÷（x-2）=5

4x-4=5(x-2)

4x-4=5x-10

x=10-4

x=6 pears are 6 kg, oranges are 4 6 = 24 kg.

In fact, elementary school math problems can be solved by turning conditions into equations.

From "the weight of the original orange is 4 times that of the pear", get the orange (original) = 4 pears (original) (1) from "the weight of the orange sold is 5 times the weight of the pear", get the orange (sell) = 5 pears (sell) (2) from "the remaining orange is 2 times the size of the pear", obtained.

Tangerine (original) - Tangerine (sell) = 2 * [pear (original) - pear (sell)] = 4 kg (3) Put (1) - (2), tidy up.

Tangerine (original) - Tangerine (sell) = 5 * [pear (original) - pear (sell)] - pear (original), so, pear (original) = 6 kg.

Tangerine (raw) = 4 pears (raw) = 24 kg.

2*2=4 (kg)·· The weight of the orange remains.

Solution: Let the pear originally weigh x kilograms, and the orange weighs 4x kilograms.

5(x-2)=4x-4

5x-10=4x-4

x=64x=24

A: Pears originally weighed 6 kilograms and oranges 24 kilograms.

The remaining oranges are twice as large as the pears, and the pears are left with 2 kilograms. The remaining oranges are 2 2 = 4 kilograms, and the ratio of selling oranges to selling pears is: 5:1

Suppose the oranges are sold for 10 kg more and the pears are sold for 2 kg more, the selling ratio remains unchanged at 5:1, but the oranges are only 4 kg, if the oranges are only sold for 4 kg more, then the ratio of oranges and pears is sold out: 4:1, so 10-4=6 is equal to the number of pears, so:

Orange = 6 * 4 = 24 kg, pear = 6 kg.

Solution: Let the original pear x kilogram be known from the meaning of the title.

It turned out that there were 4x kilograms of oranges.

The remaining oranges are 2*2=4 kg, and the pears sold are x-2 kg, and the oranges sold by the devil are 5 (x-2) kg.

There is equation 5(x-2)+4=4x

x=6 oranges have 4*6=24 kg.

A: Oranges have 24 kilograms and pears have 6 kilograms.

There are four times as many pears, five times as many pears are sold, there are two times as many pears left, and those three times are from there, it should be said that the pears are also being sold.

I'm terrible at math Let's see how to find out. Hee-hee.

If you have learned equations, it is easier to solve them with equations, and it is easy to understand ordinary solutions through equations.

I don't even know, I'm going to score two points

5 audio tapes per box 6; 2=92

x=94y=98

z = 90 x for language; Hour.

iii 13 (12-8 2) = 6; 2=96

y+z)/2=94

x+z)/.$5.

Four (x+y).5*6+

The average speed of going up and down the mountain is 10=38, the math is y, and the English is z, and the language is 94

98 in Mathematics and 90 in English

Five 800 * 4 a.

The road is repaired on average 54 meters per day.

II (30

The method is quite simple, but it is so difficult to describe in words, I don't know if you can understand the steps.

The first method: four line segments are cut in parallel to the square, and 5 rectangles with an area of 10cm 2cm are obtained.

The second method: a line segment first cuts one end of the square, so that the area of the small rectangle is 10cm 2cm; Then cut the large area with three line segments to obtain three rectangles with an area of 8cm each.

The third method: first 2 line segments cut a rectangle with an area of 10cm 2cm in the middle of the square, so that the area of both sides is equal; The other two line segments are each paired, and the remaining two parts are cut parallel to the short side, resulting in four rectangles with an area of 4 cm and 5 cm.

1 (30-12) divided by 12*100%=150%2 (30-18) divided by 18*100% is approximately equal to 67% (5*4*3-3*3*3) divided by 60*100%=55% 1-55%=45%.

I just did it alas.

The first question (30-12) 30*100%=60%, the second question (30-18) 30*100%=40%, the second question (5*4*3-3*3*3) (5*4*3)*100%=55%.

1. Question 1: (30-12) 12=18 12=

Question 2: (30-18) 18=2 3

2: (5 4 3-3 3 3) 5 4 3=

Question 1: m<2

Question 2: 1/2 of x<; x>1/2; x=1/2 of the third question: x<-5, y<-10

Question 4: C Question 5: 7

Give me a point.

1.(14 + 11/28) x 5/7

14x(5/7)+(11/28)x(5/7)=10+55/196

10 and 55/196

253.The ratio of liquid medicine to liquid medicine is: 3: (3 + 80) = 3: 8315 (3 83) = 415 (kg).

4.If there are x barrels of oil in warehouse B, then there is oil in warehouse A (5 3) x barrels (5 3) x -90 : x +90) = 2 :

33[ (5/3)x -90 ] 2(x +90)= 05x-270-2x-180=0

3x = 450

x = 150

2+1=3 (field).

Solution 1...(14 + 11/28) x 5/7 = 14 * 5 7 + 11 28 * 7 5 = 10 + 11 20 = 211 20

2, 3, unset the dispensing solution x kg.

3:80=15∶x

80*15=3x

x=4004, solution, let B have 3x barrels of oil, then A has 5x barrels.

5x-90 3x+90=2:3 The basic property of the ratio is 15x-270=6x+180

9x=450

x = 503 * 50 = 150 barrels 50 * 5 = 250 barrels 5, 2 + 1 = 3 games.

1、=（11/42）*（5/7）=55/1942、=（13+40+47）*

3, = 15 (3 80) = 400 kg.

4. Set up the original 5x box of the first warehouse, then the 3x box of B.

5x-90 3x+90=2 3, then x=50, so the original 150 in library B, 240 after adding 90 boxes

5. Elimination 2+1=3 games.

1.(a+b)c=ab+ac 14x5/7+11/28x5/7=10+55/196=2015/196

3. 3:80=15:x x=400 400+15=415kg

4.5x-90: 3x+90=2:3x=50 3x50=150 cases.

5.Draw a tree diagram. 3+2+1+2+1=9 runner-up. 9+1=10 Champions.

Question 5: You should have forgotten about the norms of elementary school. I don't know what you mean by learning probability, hehe, the rest should be right.

The first question, since it is parallel, then a, b, in one direction or in the opposite direction, when added, of course, it is consistent with the direction with the longer modulus, choose a

In the second question, if o refers to the intersection of the diagonals, the vector bc plus the vector dc is exactly the vector of their diagonal, and oc is in the same direction as them and is half of them, choose a

In the third question, which is equal to 3, you can set a'is (a, b) then aa'Perpendicular to the original straight line l, and assuming that the straight line passes the origin, then 5a+12b=0, combined with the above two equations to find b=15 13, so it is 3 times of e, equal to 3

1、a 2、a
/17

Just draw a little more sketches yourself.

(1) Select A

2) Select a o point to be the center of the rectangle.

I'm depressed, I hate math the most....

1. Let a be positive and b unknown plus or minus, then a+b>=[a]-[b]>0, which is positive 2, oc=ac can be substituted.

3 Projection definition, first calculate OA, OA and E multiplied to get.

1. Select A

If the vector a vector b, a b is in the same direction or the reverse ab is in the same direction, the vector a + vector b must be in the same direction as a.

ab reverse, |Vector a|>|Vector b|>0 gives that the vector a + vector b is in the same direction as a.

2. Choose A to draw a picture. Vector OC = 1 2 (vector AB + vector AD) = 1 2 (vector DC + vector BC).

3. Hey forgot. What do you mean by a projection on a straight line?