For a project, team a will complete it in 12 days and team B will complete it in 9 days. What is the ratio of work efficiency between team a and team B?

For a project, team a will complete it in 12 days and team B will complete it in 9 days. What is the ratio of work efficiency between team a and team B?

Team a does it alone for 12 days, so team a's work efficiency is 1 / 12
Team B alone to do 9 days to complete, then the efficiency of team B is 1 / 9
Therefore, the work efficiency ratio of team a and team B is:
1/12：1/9 = 1/12×9 =9/12 = 3/4 =34
A: the efficiency ratio of team a and team B is 3:4

When answering the question, please add the corresponding serial number in the kilometer,
① For a road construction project, it takes 9 days for team a to complete it alone and 18 days for team B to complete it alone?
② Aunt Wang sold two sets of fashion in the morning, each of which was 480 yuan. One set was 20% higher than the purchase price, while the other set was 20% lower than the purchase price. After Aunt Wang sold these two sets of fashion, how much did she actually make or lose?
③ The store bought a batch of football and sold it at 112% of the purchase price. The price of each football was 67.2 yuan. When there were no more than 50, the cost was recovered. How many football did the store buy?
④ There are two engineering teams. The first team has 120 people. If 20% of the number of the first team is transferred to the second team, two-thirds of the number of the second team is exactly three-quarters of the number of the first team. How many people are less than the first team?
⑤ Party A and Party B can complete 9 / 40 of the whole project every day when they work together. Team a works alone for 3 days and team B works alone for 5 days. After that, 1 / 8 of the whole project is left unfinished. How many days will it take to complete the whole project if team B works alone?

1.1 / 9-1 / 18 = 5.56% 2.480 / 1.2 = 400480 * 1.2 = 576480 * 2 = 960400 + 576 = 976, so the loss is 16 yuan 3.67.2 / 1.12 = 60 yuan 67.2 * 50 / 60 = 56 4.120 * 0.8 = 96 people 96 * 3 / 4 = 72 people 72 * 3 / 2 = 108 people 108-120 * 0.2 = 84 people less 120-84 = 36 people 5