Help answer and give explanation, please help answer,

x+y=640

x+y+y=720

Subtract the two formulas.

x+y+y)-(x+y)=720-640

y=80, so x=640-y=640-80=560x=(560), y=(80).

x-y=60

x+x-y=200

Subtract the two formulas.

x+x-y)-(x-y)=200-60

x=140，y=x-60=140-60=80x=(140)，y=(80)

x=560 y=80.

x=140 y=80

Big brother, you dare to come up with such a simple question.

1. Subtract the above formula from the following formula to get y=80, and substituting the above formula to get x=560.

2. Subtract the above formula from the following formula to get x=140, and substituting the above formula to get y=80.

One. x+y=640 ①

x+y+y=720 ②

Get y=80 and get x=560

Two. x-y=60 ③

x+x-y=200 ④

Get x = 140 and get y = 80

x+y=640 deformation gives y=640-x

y=640-x brings x+y+y=720

Get x+640-x+640-x=720

Get x=560 and bring back x+y=640

Get y=80

Question 2: The same is true.

I'm sorry to ask, what is this question in the book).

x+y=640 ①

x+y+y=720 ②

Formulated as x-2y=720

Substituting y=80 into the equation gives x=560 two x-y=60

x+x-y=200 ②

The formula merges 2x-y=200

Subtract the formula to get x=140 and substitute x=140 into the formula to get y=80, and then check it.

With a production cycle of 7 days, 6 people produce pants and 4 people produce clothes in 5 days; In 2 days, 5 people produced pants and 5 people produced clothes.

Make the products just right for each day: 5 people produce pants, 4 people produce clothes, 1 person produces 22 pieces of pants, and 6 pieces of clothes are produced (but must work a little extra = 1/30 of the whole shift).

In practice, the first plan should be more practical.

Obviously, if a worker can only produce clothes or pants a day, then it is more than 4 people who produce clothes to be satisfied, but there are not a few people who know it, so it is impossible to be satisfied, and someone must produce both clothes and pants. Or, don't all 10 workers go to work ===

Are the pants a piece? If so, there is no solution to this problem!!

Not necessarily.

There are four main types of dispersion of optical fibers: material dispersion, waveguide dispersion, polarization mode dispersion and intermode dispersion. Among them, inter-mode dispersion is unique to multimode fibers. In practical applications, the dispersion effects in single-mode optical fibers are mainly discussed, and the main ones are Raman dispersion, Brillouin dispersion and Rayleigh dispersion caused by the Raman effect.

The effects of these three dispersions are not the same, or even opposite. Therefore, if the time-domain widths of optical pulses measured at the incoming and outgoing locations of a certain fiber link are consistent, it is more likely that multiple dispersion effects cancel each other out, rather than no dispersion occurs.

However, this situation is only ideal, and in fact it is impossible to have an optical fiber that is completely free of dispersion.

600-440 = 160 (extra water).

5-3=2 (2 cups more).

160 2 = 80 (weight of a glass of water).

440-3*80=200 (empty bottle weight).

A glass of water weighs (600-440) (5-3) = 80 grams, and an empty bottle weighs 600-80x5 = 200 grams.

3m water + m cup = 440 grams (1).

5m water + m cup = 600 grams (2).

2)-(1) = 2m water = 160 grams.

m water = 80 grams.

440-80*3=220 grams.

It can solve the problem of hand dust for you

See figure. Hope, thank you for the potato feast.

<> is the dust argument of the faction that does this.

The correct one is 610, which sees the number of hundreds of digits subtracted as 6 as 6 and 200, and the number of tens of digits subtracted as 3 as 5 and 20 less, so 390 + 200 + 20 = 610

The numbers in the four boxes of Hu Zhi are a, b, c, d1) a+b=8

2)a+c=13

3)b+d=8

4)c-d=6

5)b-c=-5

6)b+c=14

5)+(6)→b=

Gad: a=b=

It's really hard for <> to forget you.

It's really hard for <> to forget you. ez