How to solve this math problem? Let s talk about the process, in detail.

If A makes 1 2 of the total number of the other three, then A accounts for 1 3 of the total (this can be understood), B makes 1 3 of the total number of the other three, then B accounts for 1 4 of the total, C accounts for 1 4 of the total number of the other three, then C accounts for 1 5 of the total, and D accounts for 1-(1 3 + 1 4 + 1 5) = 13 60

Total = 169 divided by 13 60 = 780

If A is made to donate as unit one, then B + C + D = 1 2 = 2 (unit one) The sum of the four people is: 1 + 2 = 3 (unit one).

B is 1 3 of the remaining three people, then it is: 3 (3 + 1) = 3 4 (unit 1) The remaining three people A + C + D = 3 -3 4 = 9 4 (unit 1) C is 1 4 of the other three people, then it is: 3 (4 + 1) = 3 5 (unit 1) the remaining three people A + B + D = 3 -3 5 = 12 5 (unit 1) A + C + D - B + C + D) = A - B = 9 4 -2 = 1 4 B = A - 1 4 =1-1 4 =3 4 D = 12 5 - A -B =12 5 - 1- 3 4 = 13 20

A = 169 13 20 = 260

Total = A 3 = 260 3 = 780

So choose A

Person A's donation: 1:3 (2+1) of the total (because the total number of the other three is two, and A's is one) 20:60

For B: 1:4 (3+1) of the total (for the other three have a total of three and B has one) 15:60

C: 1:5 (4+1) of the total (for the other three have a total of four, and C's is one) 12:60

D: 13:60 of the total

It is known that Ding donated 169 yuan, which can be known in total:

169 13 60 = 780 yuan.

Let A = x B = y C = z

2x=y+z+169 1 formula.

3y=x+z+169 2 formula.

4z=x+y+169 3 formula.

Formula 2-3 gives y=5 4*z

Formula 1-3 gives x=5 3 *z

x=260 y= 195 z= 156

AA, BB, CC, DD

2a=b+c+d （1）

3b=a+c+d （2）

4c=a+b+d （3）

d = 1691 formula minus 2 formula to get 3a = 4b

2 formula minus 4 formula to get 4b = 5c

3a=4b=5c, d=169 is substituted into 1.

a=260b=195c=156

Answer: Let there be four unknowns a, b, c, and d according to the question:

b+c+d=2a

a+c+d=3b

a+b+d=4c

169=d Find a+b+c+d=? Solve the equation to get a=260 b=195 c=156 to get a+b+c+d=780 choose a

Let the total amount be x yuan, and A's donation accounts for 1 2 of the other three people, assuming that A donates y yuan, then y=(x-y) 2, solve y=x 3 yuan, and similarly get B to donate x 4 yuan, C to donate x 5 yuan, and D to donate 169 yuan, then x=x 3+x 4+x 5+169, solve the equation to get x=780 yuan, Gu choose a answer, hope

Choose a, A, B, C, D is represented by ABCD, b+c+d 2=a, a+c+d 3=b, a+b+d 4=c, d=169, just bring d in, 3 equations and 3 unknowns This should be very simple.

Column system of equations b + c + 169 divided by 2 equals a a + c + 169 divided by 3 = b a + b + b + 169 divided by 4 equals c to solve the system of equations.

Let t=e, then t+1 t=3

It is: t -3t + 1 = 0

Solution: t=(3 5) 2

So e = (3 5) 2 x = ln[(3+ 5) 2] or ln[(3- 5) 2].

This problem can be solved according to the hook function!

1. The meaning of all knocking for 42 seconds is actually 42 seconds between the first and 7th strokes, and there are 6 intervals between 7 times, so each interval in the middle should be 42 6 = 7 seconds, so at 10 o'clock there should be 9 intervals, and finally 7 * 9 = 63 seconds.

If the clock strikes at 1 o'clock, it strikes 7 times at 7 o'clock = 42 seconds, and each time = 42 7 = 6 seconds.

Hit 10 times at 10 o'clock = 6 10 = 60 seconds.

7 hits at 7 o'clock, 6 time intervals = 42 seconds, 7 seconds between every two hits.

Knock 10 times at 10 o'clock, which is 9 intervals = 63 seconds.

I didn't have this question a few days ago.

Connect the dots du within the square with the four corners.

Then, the area of the triangle of equal height is equal to the same bottom, and the corresponding area of the triangle on each side is assumed.

a, b, c and d

then there is a+b=16

b+c=20 ②

c+d=32 ③

Finding a+d, obviously, + yields.

The area sought is.

1. Draw a big circle.

2. Use a ruler to draw two diameters perpendicular to each other.

3. Draw the center of each radius with the midpoint of the circle, and draw a semicircle with a radius of diameter, a total of four 4, and draw eight smaller semicircles in a similar operation.

Tips and tricks:

1.Make auxiliaries from the vertices to the intersection of the large square;

2.The principle of equal volume of triangular plates of equal height is used;

3.If the weights of both sides of the equation are added or subtracted at the same time, the equation still holds;

5.Correct answer: 28cm squared.

Area = 32 + 16 - 20 = 28

Make a line with an angle through the middle point, and the two triangles on each side are equal in area, and the column equation can be found to be 20+? =a+b+c+d

16+32=a+b+c+d

So 16+32=20+? , I don't understand this.

The area on the two diagonal corners is equal:

32 dec. 16 a 20

48-20=28

Suppose the original rice has x kilograms.

Sell in the first week x 2+300 and leave x 2-300 in the second week (x 2-300) 2-250

There are 750 left, so there is x 2+300+(x 2-300) 2-250+750=x, and the solution gets x=2600

Set the original rice x kg.

x/2-300）/2-250=750

x = 4600 (kilograms).

7th grade: 80n+80 1 2 m=80n+40m8th grade: 80 5 2n+40 3 2m=200n+60mTotal:

80N+40M+200N+60M=280N+100MWhen M=30, N=10, the total savings after discount: 280N