For a bottle of alcohol, pour out two-thirds and 20 grams at the first time, then pour back 35 grams, and pour out 50% of it at the second time. At this time, there is 45 in the bottle, how much is the original I want arithmetic. I want meaning,

For a bottle of alcohol, pour out two-thirds and 20 grams at the first time, then pour back 35 grams, and pour out 50% of it at the second time. At this time, there is 45 in the bottle, how much is the original I want arithmetic. I want meaning,

45 g is 50% of the remaining alcohol: 45 / 50% = 90
Remaining after the first pour: 90-35 = 55
Two thirds of the original alcohol: 55 + 20 = 75
Original alcohol: 75 / (2 / 3) = 112.5
Not 225 grams

19 out of 20, 4 out of 15 and 18 out of 75

The minimum denominator of denominator 20 15 75 is 300
therefore
19 out of 20 = 285 out of 300
4 out of 15 = 80 out of 300
18 out of 75 = 72 out of 300

It is known that 3 / 5 tons of soybean can extract 9 / 20 tons of oil, then the formula 9 / 20 divided by 3 / 5 represents (), and the formula 3 / 5 divided by 9 / 20 represents ()
It is known that 5 / 3 tons of soybean can extract 9 / 20 tons of oil, then the formula 9 / 20 divided by 3 / 5 is () and the formula 3 / 5 divided by 9 / 20 is ().
What it means is to write arithmetic.

How many tons of oil can be squeezed per ton of soybean
How many soybeans do you need per ton of oil

Given the complete set u = Z, a = {x | x = 2K, K ∈ Z}, B = {x | x = 2K + 1, K ∈ Z}. Find the complements of a and B

∵A∪B=U,A∩B=∅
The complement of a is B, and the complement of B is a

From 1-100 integers, find 8 numbers and make their reciprocal sum equal to 1

1=60/60=(1+2+3+4+5+10+15+20)/60
=1/60+2/60+3/60+4/60+5/60+10/60+15/60+20/60
=1/60+1/30+1/20+1/15+1/12+1/6+1/4+1/3

Simple operation (68-7 / 18) multiply 1 / 17 (2 / 3-5 / 9 multiply 3 / 8) divide 5 / 16
(2-1 / 12 + 1 / 8) times 12
(4 divided by 3 / 5-5) divided by 2 / 3
3 / 5 divide [(3 / 4-2 / 3) divide by 5 / 6] multiply by 1 / 8

(68-7 / 18) times 1 / 17 = 68 times 1 / 17-7 / 18 times 1 / 17 = 4-7 / 306 = 3 and 299 / 306 (2 / 3-5 / 9 times 3 / 8) divided by 5 / 16 = 2 / 3 * 16 / 5-5 / 9 * 3 / 8 * 16 / 5 = 2 / 3 * 16 / 5-2 / 3 = 2 / 3 * (16 / 5-1) = 22 / 15 (2-1 / 12 + 1 / 8) × 12 = 2 × 12-1 / 12 × 12 + 1 / 8 × 12 = 24-1 + 1.5 = 24

The simple method is 4 / 9 + 3 / 17 + 5 / 9 + 14 / 17

4 / 9 + 3 / 17 + 5 / 9 + 14 / 17
=4 of 9 + 5 of 9 + 3 of 17 + 14 of 17
=1+1
=2

How to factorize x ^ 4 + ax ^ 2 + BX + C

Four roots x1, X2, X3, X4 are obtained by using the root formula of quartic equation
Then x ^ 4 + ax ^ 2 + BX + C = (x-x1) (x-x2) (x-x3) (x-x4)

(minus 6) multiply by (minus 1 / 2 + 1 / 3) (1 / 4 minus 1 / 2 plus 1 / 6) multiply by 12 (minus 1002)
How much is (minus 6) multiplied by (minus 1 / 2 + 1 / 3) (1 / 4 minus 1 / 2 plus 1 / 6) multiplied by 12 (minus 1002) multiplied by 17,

(minus 6) multiply (minus 1 / 2 + 1 / 3)
=6×1/2-6×1/3
=3-2
=1
(1 / 4 minus 1 / 2 plus 1 / 6) times 12
=1/4×12-1/2×12+1/6×12
=3-6+2
=-1
(minus 1002) times 17
=-1000×17-2×17
=-17000-34
=-17034

The math teacher is going to make a 20 cm long, 10 cm wide and 3 cm high rectangular frame with iron wire as a teaching aid. Is 1.5 m long iron wire enough

4 × (20 + 10 + 3) = 132cm = 1.32M, enough