Typical problems in practical engineering problems For a project, it takes 20 days for team a to do it alone, and 12 days for team B to do it alone. It is known that team a has done the project for several days, and then team B has continued to complete it. It takes 14 days from the beginning to the completion, so how many days did team a do it first? How many days did Team B do it again?

Typical problems in practical engineering problems For a project, it takes 20 days for team a to do it alone, and 12 days for team B to do it alone. It is known that team a has done the project for several days, and then team B has continued to complete it. It takes 14 days from the beginning to the completion, so how many days did team a do it first? How many days did Team B do it again?

The solution of this engineering problem by concentration method
Regard the whole project as "1"
The completion time ratio of Party A and Party B in 14 days is as follows:
（20-14）:（14-12）= 3：1
Time is inversely proportional to work efficiency, which is 1:3
Team a did it first: 20 × 1 / (1 + 3) = 5 (days)
Team B did it again: 14-5 = 9 (days)

This year's Spring Festival Tourism Golden Week has ended. According to relevant statistics, from the first day of the first month to the seventh day of the first month, all scenic spots and scenic spots in the province receive tourists from inside and outside the province
With 1.22 million person times, the total tourism income reaches 480 million yuan, of which the per capita consumption of tourists inside and outside the province reaches 169 yuan and 1200 yuan respectively. Find out the person times of tourists inside and outside the province

Suppose the number of people in the province is x and the number of people outside the province is y, then x + y = 1220000, and the second equation is 169x + 1200y = 480000000. Solve it by yourself and substitute x = 1220000-y of the first equation into the second equation

After the end of the golden week, according to relevant statistical reports, October 1 to 7
There are 1.22 million tourists inside and outside the province, and the total tourism income is 476 million yuan, of which the per capita consumption inside and outside the province is 4 yuan, 160 yuan and 1200 yuan respectively. What are the number of tourists inside and outside the province?

Set the number of people in the province as X 10000, and the number of people outside the province as y 10000
X+Y=122
160X+1200Y=47600
X = 950000
Y = 270000

As shown in the picture, there is a grotesque Wangtian cave in a tourist area. Point D is the entrance of the cave. After tourists enter the cave from the entrance, they can enjoy the scenery,
Number of visits: 1 Reward: 5 | 14 days and 23 hours to the end of the question | questioner: cx123995
In the same plane, if the length of slope BD is 100 meters, the slope angle is ∠ DBC = 10 °, the elevation angle of a measured at B is ∠ ABC = 40 ° and the elevation angle of a measured at d is ∠ ADF = 85 ° make a vertical line of ground · be, and the vertical foot is C
1) Find the degree of ∠ ADB
2) Finding the length of cableway ab

（1）∵DC⊥CE,
∴∠BCD=90°．
And ∵ ∠ DBC = 10 °,
■ ∠ BDC = 80 ° (1 point)
∵∠ADF=85°,
■ ∠ ADB = 360 ° - 80 ° - 90 ° - 85 ° = 105 ° (2 points)
(2) DG ⊥ AB at point g. (3 points)
In RT △ GDB,
∠GBD=40°-10°=30°,
∴∠BDG=90°-30°=60°．
And ∵ BD = 100,
∴GD= BD=100× =50．
∴GB=BD×cos30°=100× =50 ．
When RT △ ADG = 105 ° - 60 ° = 45 °,
∴GD=GA=50．
∴AB=AG+GB=50+50 ．
A: the cableway is 50 + 50 meters long

The following table lists the time difference between several foreign cities and Beijing, city time difference / time New York - 13 Paris - 7 Tokyo + 1 Chicago - 14 when Chicago time is up

It's 13:00 in Tokyo
No, it's 1 a.m. local time in New York