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（1）2—（1—y）=—2 （2）5—（x—1）=3—3x （3）3—2（2x+1）=2（x—3）（4）4x—3（20—x）=6x—7（9—x） （5）12（2—3x）=4x+4 （6）2（200—15x）=70+25x （7）4x—3（20—x）+4=0 （8）1—3（8—x）=—2（15—2x）
2—（1—y）=—2
2-1+y=--2
y=-2-2+1=-3
（2）5—（x—1）=3—3x
5-x+1=3-3x
2x=3-1-5
2x=-3
x=-1.5
（3）3—2（2x+1）=2（x—3）
3-4x-2=2x-6
6x=3-2+6
6x=7
x=7/6
（4）4x—3（20—x）=6x—7（9—x）
4x-60+3x=6x-63+7x
7x-60=13x-63
6x=3
x=0.5
（5）12（2—3x）=4x+4
24-36x=4x+4
40x=20
x=0.5
（6）2（200—15x）=70+25x
400-30x=70+25x
55x=330
x=6
（7）4x—3（20—x）+4=0
4x-60+3x+4=0
7x=60-4=56
x=8
（8）1—3（8—x）=—2（15—2x）
1-24+3x=-30+4x
x=1-24+30=7
I'm tired. I'm looking for extra points,
(6) 3:5y + 4 + 4:y-1 = 2-12:5y-5 (7) 3:4-8x = 3-2:11x (8) 0.5x-0.7 = 6.5-1.3x (9) 6:1 (3x-6) = 5:2x-3 (10) 3:1-2x = 7:3x + 1-3
(6) 5Y of 3 + 4 + y of 4-1 = 5Y of 2-12, 4 (5Y + 4) + 3 (Y-1) = 24 - (5y-5) 20Y + 16 + 3y-3 = 24-5y + 518y = 16y = 8 / 9 (7) 4-8x of 3-11x of 2, 2 (4-8x) = 18-3 * 11x8-16x = 18-33x17x = 10x = 10 / 17 (8) 0.5x-0.7
Class 5 (2) issues new books. If each person issues 5 books, there will be 5 more books. If each person issues 6 books, there will be 4 people who have not received them. How many students are there in this class? How many new books are there?
Suppose there are X students in this class, then 5x + 5 = 6 (x-4), x = 29
Number of books: 5 * 29 + 5 = 150
A project is completed in 20 days by Party A and 30 days by Party B. now Party A and Party B cooperate and have a few days off due to illness
It's better not to be an equation, it's better to be a formula, and it's better to explain it step by step
For a project, Party A works alone for 20 days, and Party B works alone for 30 days. Now Party A and Party B work together. Party B takes a few days off due to illness. After 14 days from commencement to completion, how many days has Party B taken off?
In fact, this problem is not difficult. Just listen to me slowly
A completes the project in 20 days alone, which means that the speed of a is one twentieth of that of a day. Similarly, the speed of B is one thirtieth of that of a day. Suppose that B takes X days off in the process of cooperation, then the equation is as follows:
1/20*14+1/30*(14-X)=1
1 in the equation is engineering, if you don't understand, you can set it as y, but when calculating, y is on both sides of the equation and can be reduced
In fact, it's very interesting for you to think more about math problems, and you will have a sense of achievement after solving them. Ha ha, I wish you a happy New Year!
For a project, team a finished it in 20 days and team B finished it in 30 days. Now they are working together. Team a took three days off and team B took several days off. It took 16 days from the beginning to the completion. How many days did Team B take off?
[120 × (16-3) + 130 × 16-1] △ 130, = [1320 + 1630-1] × 30, = [3960 + 3260-1] × 30, = 1160 × 30, = 5.5 (days); answer: Team B had a rest of 5.5 days
For a project, team a finished it in 20 days and team B finished it in 30 days. Now they are working together. Team a took three days off and team B took several days off. It took 16 days from the beginning to the completion. How many days did Team B take off?
[120 × (16-3) + 130 × 16-1] △ 130, = [1320 + 1630-1] × 30, = [3960 + 3260-1] × 30, = 1160 × 30, = 5.5 (days); answer: Team B had a rest of 5.5 days
For a project, team a finished it in 20 days and team B finished it in 30 days. Now they are working together. Team a took three days off and team B took several days off. It took 16 days from the beginning to the completion. How many days did Team B take off?
[120 × (16-3) + 130 × 16-1] △ 130, = [1320 + 1630-1] × 30, = [3960 + 3260-1] × 30, = 1160 × 30, = 5.5 (days); answer: Team B had a rest of 5.5 days
For a project, team a finished it in 20 days and team B finished it in 30 days. Now they are working together. Team a took three days off and team B took several days off. It took 16 days from the beginning to the completion. How many days did Team B take off?
[120 × (16-3) + 130 × 16-1] △ 130, = [1320 + 1630-1] × 30, = [3960 + 3260-1] × 30, = 1160 × 30, = 5.5 (days); answer: Team B had a rest of 5.5 days
For a job, it takes 20 days for a to do it alone, and 30 days for B to do it alone. Now they work together. In the middle, a takes three days off, and B takes several days off,
Share 16 days to complete, how many days does B rest?
\Hello
I think like this, a 20 days to complete, every day 1 / 20; B 30 days to complete, every day 1 / 30; work together, do not rest, need 1 (1 / 20 + 1 / 30) = 12 days. Now shared 16 days, then a and B rest 16-12 = 4 days
At this time, if a takes 3 days off, B can do 1 / 20 less (A's workload in one day), which is equivalent to that B can take 1 / 20 more (1 / 30 = 1.5 days)
Therefore, on the basis of 4 days' rest, B took an extra 1.5 days, a total of 5.5 days
above.
Now the two teams are working together. In the middle of the road, team a has a rest of 2.5 days, and team B has a rest of several days. In this way, the road can be repaired in 14 days. How many days has team B had a rest?
A's work efficiency is 120, B's work efficiency is 130, a's actual repair time: 14-2.5 = 11.5 & nbsp; (days), a's workload: 120 × 11.5 = 2340, B's work time: (1 − 2340) △ 130 = 1740 △ 130 = 1740 × 30 = 12.75 (days), B's rest time: 14-12.75 = 1.25 (days)
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