A problem of linear equation with one variable in grade one mathematics of junior high school The electricity charge of a factory in the first quarter was a yuan, and the water charge was 40 yuan more than twice the electricity charge. In the second quarter, the electricity charge was saved by 15%, and the water charge was 38% more. Q: compared with the first quarter, the water charge of the factory in the second quarter was overspent or saved? How many yuan was overspent or saved? List the equations

Total money spent in the first quarter a + 2A + 40 = 3A + 40
Q2 a (1-0.15) + (2a + 40) (1 + 0.38) = 0.85a + 2.76a + 55.2 = 3.61a + 55.2
Overspending
3.61a+55.2-3a-40=0.61a+15.2

One variable equation of first degree and its application

Let (what) be X
(and then the formula)
(then)
Both sides can add, subtract, multiply and divide the same number at the same time, and the equality remains unchanged
For example: x + 1 = 2
Then add both sides and subtract one at the same time
X+1-1=2-1
X=1

Is there a formula for the problem of cattle eating grass?

(1) The growth rate of grass = the corresponding number of cattle × the number of days to eat more - the corresponding number of cattle × the number of days to eat less (the number of days to eat more - the number of days to eat less);
(2) The original grass amount = the number of cattle × the number of days to eat - the growth rate of grass × the number of days to eat`
(3) The number of days to eat = the original amount of grass (the number of cattle - the growth rate of grass);
(4) The number of cattle = the original amount of grass △ the number of days to eat + the growth rate of grass

Find the formula of the distance from the space point to the plane,
The distance from a point outside the plane P (x, y, z) to the plane ax + by + CZ = D

Given cos (π / 2 + a) = 2Sin (a - π / 2), find sin (π - a) + cos (a + π)/
Find sin (π - a) + cos (a + π) / 5cos (5 π / 2-A) + 3sin (7 π / 2-A)

If cos (π / 2 + a) = 2Sin (a - π / 2), sin (π - a) + cos (a + π) / 5cos (5 π / 2-A) + 3sin (7 π / 2-A) is known to be Sina = 2cosa (using the induced formula), then sin cosa / 5sina-3cosa (using the induced formula), the title means (Sina COSA) / (5sina-3cosa))

Pinyin exercises in primary school Chinese

First grade exercise example [Pinyin] 1 circle the initials, finals and syllables you hear. ① n 1, ② C sh ③ uiiu, ④ in ing, ⑤ Hu á I Hu á ⑥ Xi Xu ě ⑦ B á P á Ⅷ sh ē n sh ē NG2 connect the syllables and words

Given that n > 1 and N belongs to n *, prove logn (n + 1) > logn + 1 (n + 2)

Logn (n + 1) = LG (n + 1) / lgnlg (n + 1) (n + 2) = LG (n + 2) / LG (n + 1) obviously verify that LG (n + 1) / LGN and LG (n + 2) / LG (n + 1) can simultaneously subtract 1 (LG (n + 1) - LG n) / LGN (1) and (LG (n + 2) - LG (n + 1)) / LG (n + 1) (2 (LG (n + 1) - LG n) = LG ((n + 1) / N) (LG (n + 2) - LG (n + 1))

a+b+c=0 4a+2b+c=4

Two equations can't solve three unknowns. Is there any restriction

1999×19981998-1998×19991999

1999×19981998-1998×19991999=2000×19981998-19981998-2000×19991999+2×19991999=19991999×2-19981998-2000×10001=19991999+19991999-19981998-20002000=10001-10001=01999×19981998-1998×19991999=1999×1...

On the pronunciation of Putonghua
It's OK for me to speak Putonghua, but the pronunciation of some words is very similar to that of Hong Kong and Taiwan. For example, when I pronounce the word "yes", the word "yes" is tongue curling, and I also pronounce tongue curling, but the ending sounds like a whistle. As long as I encounter tongue curling, something like this will happen
I want to know how to change this?

The most basic way is to follow the news broadcast every day, but it's not easy to insist on. Another way is to open your mouth a little bit when you read the tongue curling sound, which may be useful