If a book is priced at 45 yuan, it will make 50% profit after it is sold. If it is sold at 20% discount, how much profit can it make?

If a book is priced at 45 yuan, it will make 50% profit after it is sold. If it is sold at 20% discount, how much profit can it make?

Purchase price: 45 divided by (1 + 50%) = 30 yuan
45 * 80% = 36 yuan
36-30 = 6 yuan
Answer: can profit 6 yuan

If a commodity is sold at 80% of the price, it can still get 20% profit. What is the expected profit in the pricing period______ ．

Suppose the price is 1, then the current price is: 1 × 80% = 0.8; 0.8 △ 1 + 20%, = 0.8 △ 120%, = 23; (1-23) △ 23, = 13 △ 23, = 50%; a: the expected profit in the pricing period is 50%. So the answer is: 50%

The price of a book has been reduced by 50%. Now, it is sold at the original price, which is increased by several percent
How to calculate this problem,

Solution:
Let the original price be 1
Then the price after reduction is 1-1 × 50% = 0.5
Now we have to raise the price from 0.5 to 1,
The increase range is
(1-0.5)÷0.5=100%.
A: increased by 100%

The average number of a, B and C is 6, and their ratio is one-half: two-thirds: five sixths. What is the number of a, B and C?

1/2:2/3:5/6=9:12:15
A 6x3x9 △ (9 + 12 + 15) = 4.5
B 4.5x12/9 = 6
C 4.5x15/9 = 7.5

It is known that a and B are positive numbers, the root sign a + the root sign B

Divide √ (a + b) to the left, because √ is greater than 0, so t > 0, square the formula to the left and right, you can get 1 + (2 √ (AB) / (a + b)), 2 √ (AB)

The ratio of a and B is 1:2, and the sum of them is 360. A is () B is ()

The number of a is: 360 × 1 △ 1 + 2 = 360 △ 3 = 120
B: 360 × 2 △ 1 + 2 = 720 △ 3 = 240

If x = 8 is the solution of the equation AX + 1 = 10-4a, then a = ()

If x = 8 is the solution of the equation AX + 1 = 10-4a,
Namely
8a+1=10-4a
12a=9
a=3/4

50% of a is equal to 9 / 8 of 108. B is 3 / 5 of A. what's B

A number: 108x9 / 8 △ 50% = 243
B number: 243x3 / 5 = 145.8

Let a be a matrix of 4 * 5 and rank (a) = 2, then why is the number of vectors contained in the basic solution system of the second system AX = 0 3?
I hope that under the guidance of elder brothers and sisters, let me understand!

Ax = 0, a is 4 × 5, X is 5 × 1
So the number of vectors contained in the basic solution system = 5-r (a) = 3
Here we use that formula, the number of vectors of the basic solution system = N-R (a)
Your question may be how to take this n, this n should take the dimension of X column vector

It takes six minutes to make a part, five minutes to make B part and four and a half minutes to make C part. Now there are 1590 parts, which are assigned to three of them and are required to be completed in the same time. How many parts should each of them assign?

Find out the minimum number of parts each of three people can complete in the same time
Time t = 6 * 5 * 4.5 * 2 = 270 minutes, in t time, a completed 45, B completed 54, C completed 60
Therefore, three people completed 159 in t time, and it took 10 t time (2700 minutes) to complete a total of 1590. The amounts allocated to three people were 2700 / 6 = 4502700 / 5 = 5402700 / 4.5 = 600