In order to reward the progress of learning machine, a class in Grade 9 bought a notebook with a unit price of 3 yuan and a pen with a unit price of 5 yuan, which cost 35 yuan in total. How many schemes are there?

In order to reward the progress of learning machine, a class in Grade 9 bought a notebook with a unit price of 3 yuan and a pen with a unit price of 5 yuan, which cost 35 yuan in total. How many schemes are there?

There are two options
Plan 1: 5 notebooks and 5 pens
Plan 2: 10 notebooks and 1 pen

A unit ordered 22 boxes of boxed lunch in a fast food restaurant, which cost 140 yuan. There are three kinds of boxed lunch: A, B and C. their unit prices are 8 yuan, 5 yuan and 3 yuan respectively
So what are the possible different ordering plans

Let a, B and C fix x, y and Z boxes respectively, then x > 0, Y > 0, z > 0 x + y + Z = 22, that is, z = 22-x-y, y = 22-x-z, 8x + 5Y + 3Z = 140, and substitute Z to get 8x + 5Y + 66 - 3x - 3Y = 140, that is, 5x + 2Y = 74

There are the following activities for purchasing books: 10% off for 1-19 books; 7% off for more than 20 books (including 20), 5 yuan for each
At present, people buy 30 books twice at a total cost of 129 yuan. How many books do they buy each time,

If every time you buy a book is less than 20, there will be a result of 30 * 4.5 = 135, then there must be a time greater than 20 and a time less than 20
Let's set one X copy and one y copy,
X+Y=30；（1）
3.5X+4.5Y=129；（2）
(1) Formula equal sign about * 3.5 get 3.5x + 3.5y = 105 (3)
(2) Equation - (3) gives y = 5
We can get x = 25 and y = 5, that is 25 copies at a time and 5 copies at a time

The last page of exercises and evaluation in the second class of the ninth grade of Mathematics
It is known that: as shown in the figure, P is a moving point on the diameter ab of circle O (P does not coincide with a), PD ⊥ AB, the perpendicular foot is p, DC tangents circle O to C (DC is on the left side of DP), connects BC to PD to E
(1) Compare the size of DC and De, and prove that: (2) if the radius of circle O is 3 √ 3, PD = 7. As shown in Figure 3, when the point P moves to where, d = 60?

1: If ∠ OCB = ∠ OBC, and ∠ OCB + ∠ DCE = 90 degree, ∠ PBE + ∠ PEB = 90 degree, then ∠ Dec = ∠ DCE, so it is isosceles triangle, DC = de2: let de = x, because ∠ d = 60, so ∠ e = ∠ DCE = 30 degree, then EC = √ 3Ed = √ 3x, and △ OCB is equilateral triangle (∠ B = 90 - ∠ e = 60 degree), BC = OC = 3 √ 3, consider straight

Calculation: 77 degrees 53 minutes 26 seconds + 33 degrees 12 minutes 42 seconds =?

77 degrees 53 minutes 26 seconds + 33 degrees 12 minutes 42 seconds
=110°65′68″
=111°6′8″

Words to describe girls' indifference
The more the better~

Indifference, cold face, indifference, cold face, iron face, numbness, numbness, silence, coldness, coldness, cold blood, coldness
Indifference, indifference, expressionless
Cold and arrogant, cold and stern, cold and fierce, cold and indifferent

Quarter + Half=
Two fifths + three fourths=
Three quarters - two fifths=
Half and two fifths=
Two out of seven plus two out of five=
Three tenths plus two fifths=
Five eighths minus one half=
Three quarters minus one half=
Nine tenths minus one half=
① There are two oil barrels. One third of the oil in barrel a is one sixth of the kilogram more than that in barrel B. how many kilogrammes are there in both barrels a and B?
② There are two fifths of the total area of wheat, three eighths of the total area of soybean, the rest is corn
(1) What percentage of the total area are wheat and soybean planted?
(2) What percentage of the total area is corn planted?

1/4+1/2
=1/4+2/4
=3/4
2/5+3/4
=8/20+15/20
=23/20
3/4-2/5
=15/20-8/20
=7/20
1/2+2/5
=5/10+4/10
=9/10
2/7+2/5
=10/35+14/35
=24/35
3/10+2/5
=3/10+4/10
=7/10
5/8-1/2
=5/8-4/8
=1/8
3/4-1/2
=3/4-2/4
=1/4
9/10-1/2
=9/10-5/10
=4/10
=2/5
① B barrel oil = 1 / 3-1 / 6
=2/6-1/6
=1 / 6kg
A and B two barrels of oil = 1 / 3 + 1 / 6
=2/6+1/6
=3/6
=1 / 2kg
②
(1)：
2/5+3/8
=16/40+15/40
=31/40
Wheat and soybean accounted for 31 / 40 of the total area
(2)：
1-31/40
=40/40-31/40
=9/40
Corn accounts for 9 / 40 of the total area

3 (x-3) = 4x-21 to solve the equation

3x-9=4x-21
3x-4x=9-21
-x=-12
x=12

Simple calculation 125 times 25 times 3

125 by 25 by 3
=25x25x15
=25x25x(16-1)
=25x25x16-25x25
=25x4x(25x4)-625
=10000-625
=9375

The coordinate of point a is (1,0) and point B moves on the line y = - X. when line AB is the shortest, what is the coordinate of point B?

In the shortest time, the line image of AB is perpendicular to y = x, and the line AB is set as y = - x + K, because it is over (- 1,0), so the AB equation is y = - X-1
Y = x and y = - X-1, x = - 1 / 2, y = - 1 / 2. So the coordinates of point B are (- 0.5, - 0.5)