Team a and team B build two equal sections of highway at the same time. After 12 days of construction, the workload completed by the two teams is just equal to the total workload of team A. after 20 days of construction, team B has completed the task, and team a still has 300 meters to complete. What is the total length of these two sections of highway?

Team a and team B build two equal sections of highway at the same time. After 12 days of construction, the workload completed by the two teams is just equal to the total workload of team A. after 20 days of construction, team B has completed the task, and team a still has 300 meters to complete. What is the total length of these two sections of highway?

Set a day to complete
B's work efficiency = 1 / 20
A's work efficiency = 1 / A
（1/a+1/20）×12=1
1/a=1/12-1/20
1/a=8/（12×20）
1/a=1/30
A = 30 days
Then the total length of the two sections of highway = 2 × 300 / (1-20 / 30) = 1800 meters
Arithmetic:
Consider the length of each section as unit 1
Then the efficiency of B = 1 / 20
B: 1 / 20 × 12 = 3 / 5 in 12 days
Then the efficiency of a = (1-3 / 5) / 12 = 1 / 30
A: 1 / 30 × 20 = 2 / 3 in 20 days
Length of each section = 300 / (1-2 / 3) = 900 m
Total length of two sections = 900 × 2 = 1800 m

Party A and Party B rush to repair a railway section of the same length at the same time. After 12 days of construction, the workload of the two teams is just equal to the total workload of Party A. after 20 days of construction, team B completes the task, and team a needs to repair another 400 meters to complete the task______ Rice

The efficiency of Party B is 120, that of Party B is 120 × 12 = 23 in 12 days, that of Party A is 1-35 = 23 at that time, that of Party A is 25 △ 12 = 130, that of Party A is 130 × 20 = 23 after 20 hours of construction, that of each section of road is 300 △ 1-23 = 900 (m), that of two sections of road is 900 × 2 = 1800 (m), and that of two sections of road is 1800 (m)

Team a and team B rush to repair two short railways with the same length at the same time. After 12 days of construction, team B has completed the task, and team a needs to build another 300 meters to complete the task. Q: how many meters are the total length of the two railways?

How do you feel that you copied the wrong question

For the construction of a section of railway, team a can complete it in 15 days, while team B can complete it in 18 days. Now the two teams work together for 5 days, and the rest is done by team B alone. How many days will it take team B to complete it?

Seven days
[1-(1/15+1/18)*5]/(1/18)=7