Team a and team B built a road together. When they finished the task, team a built 815% of the road. If team B finished it alone in 24 days, how many days did team a finish it alone? (Qingshan District, Wuhan City)

Team a and team B built a road together. When they finished the task, team a built 815% of the road. If team B finished it alone in 24 days, how many days did team a finish it alone? (Qingshan District, Wuhan City)

The working time of team a and team B: (1-815) △ 124, = 715 × 24, = 565 (days); team a does it alone for several days: 1 △ 815 △ 565, = 1 △ 121, = 21 (days). Answer: team a does it alone for 21 days

Party A and Party B build a road together. When completing the task, Party A builds 8 / 15 of the road. If Party B finishes the task alone, how many days will team a finish it alone?

（1-8/15）÷8/15=7/8
1 / 24 / 7 / 8) = 21 (days)
A: team a does it alone for 21 days

Team a and team B build a road. If team B does it alone, it will take 15 days to finish it. Now both teams build it at the same time. When it is finished, team a builds 7 / 13 of the total length. It is known that the two teams build it every day
Team a and team B build a road. If team B does it alone, it will take 15 days to finish. Now the two teams are building at the same time. When they finished, team a built 7 / 13 of the total length of the road. It is known that the two teams build 3 / 15 of 7 kilometers a day. How many kilometers is the road?

Analysis: when finished, team a repaired 7 / 13 of the total length, then team B repaired 1-7 / 13 of the total length = 6 / 13. The time taken by team B to repair 6 / 13 is the time for two teams to work together. If the work efficiency of two teams is known, then the total length can be calculated
The formula is (1-7 / 13) / (1 / 15) × 3 and 7 / 15
=6 / 13 ÷ (1 / 15) × 3 and 7 / 15
=24 (km)