Fill in the appropriate prime numbers in the brackets below 20=（ ）+（ ）=（ ）-（ ） 26=（ ）+（ ）=（ ）+（ ）+（ ） 50=（ ）+（ ）=（ ）+（ ）+（ ）

Fill in the appropriate prime numbers in the brackets below 20=（ ）+（ ）=（ ）-（ ） 26=（ ）+（ ）=（ ）+（ ）+（ ） 50=（ ）+（ ）=（ ）+（ ）+（ ）

20=（ 3 ）+（17 ）=（23）-（3 ）
26=（ 23 ）+（ 3 ）=（ 2 ）+（11 ）+（13 ）
50 = (3) + (47) = (2) + (17) + (31), please adopt it in time!

() + () = 15 () + () = 8 () + () = 34 () + () = 20 prime number required

2+13=15 3+5=8 3+31=34 3+17=20

The temperature of a city is 23 degrees in the morning, 6 degrees higher at noon than in the morning, and 13 degrees lower at night than at noon. What is the temperature of that night?

16 degrees

If the two solutions of the equation MX + NY = 6 are x = 2, y = 1, x = 1, y = 2, then M = n=
Before 13:50

Directly substitute 2m + n = 6 m + 2n = 6
M = n = 2

6 / 5m: 36cm reduction ratio

6 / 5m: 36cm = 120cm: 36cm = 10:3

Denominator elimination of linear equation with one variable
2X / 4 + 1 - X-1 / 2 = 2
3% y + 4 - y + 5 = 3% y = 3 - 2% Y-2

1. Multiply both sides by 4 to get 2x + 1-2 (x-1) = 8, then you can do it yourself;
2. How can there be two equal signs? Is there a wrong number

(23 / 66 + 55 / 46 + 10 and 5 / 11) simple operation of x23 / 11

Solution (23 out of 66 + 46 out of 55 + 10 out of 11) x 11 out of 23
=(23 / 66 + 46 / 55 + 115 / 11) x 11 / 23
=23 of 66 * 11 of x23 + 55 of 46x23 + 11 of 11 of 11 of 11 + 11 of 115x23
=1/6+2/5+5
=5 and 17 / 30

The line L passes through the point a (2.4), where l is cut by L1: X-Y + 1 = 0, L2: x-y-2 = O. the midpoint of the line is on the line L3: x + 2y-3 = 0. The equation of the line is obtained

This problem has a wide way of thinking and flexible solution. To solve the equation of a straight line, its slope can be obtained first. For this reason, the midpoint can be expressed. If the midpoint is on a straight line, it can be obtained. To solve the equation of a straight line, the coordinate of a point on a straight line can be obtained first, and then the equation can be obtained by combining it with a point

Mathematics problems in grade one of junior high school
1. Forge round steel with diameter of 6cm and length of 16cm into round steel with radius of 4cm, and calculate the length of the forged round steel
2. A 120cm long fence is used to form a rectangular vegetable field (the wall can be used as a long side of the vegetable field, and the other three sides are enclosed by a fence), so that the length of the vegetable field is twice the width, and the area of the vegetable field can be calculated
3. It is known that the diameter of the bottom surface of the cylinder is 60mm and the height is 100mm, and the diameter of the bottom surface of the cone is 120mm, and the volume of the cylinder is half more than that of the cone
4. Use a 86cm long wire to form a rectangle
(1) Make the width of the rectangle 7cm smaller than the length
(2) Make the length and width of the rectangle equal, and the area of the rectangle is different from (1)?

I'll make you an equation and solve it by yourself
1. Set length X
（6÷2）²*π*16=4²*π*X X=36
2. Set width X
2X+2X=120 X=30
Then multiply the length by the width
four point one
Set width X
2（2X+2（X+7））=86 X=18
4.2 self comparison

As shown in the figure, it is known that ad is the middle line of △ ABC, ad = AC, ed ⊥ BC, CE and ad intersect at point F. verify that point F is the middle point of AD
Such as the title

Through a as Ag ⊥ BC in G
AG to CE in H
Because BD = CD, CG = DG
So BD / BG = 2 / 3, CG / CD = 1 / 2
So de / Ag = 2 / 3, Hg / de = 1 / 2
So Hg / Ag = 1 / 3
So ah = de
Because ah ‖ de
So △ def ≌ △ AHF
So DF = AF