1. A freighter travels an average of 48 kilometers per hour. It takes 5 hours to get from port a to port B. when it returns, it goes against the current, and its speed is one sixth slower than that in the current. How long does it take for this freighter to go back and forth? 2. It will take 10 days for the two engineering teams to complete a project together. Now team a will do it for three days, and then team B will do it for four days. Three eighths of the project will be completed. How many days will it take for the two teams to complete the project independently?

1. A freighter travels an average of 48 kilometers per hour. It takes 5 hours to get from port a to port B. when it returns, it goes against the current, and its speed is one sixth slower than that in the current. How long does it take for this freighter to go back and forth? 2. It will take 10 days for the two engineering teams to complete a project together. Now team a will do it for three days, and then team B will do it for four days. Three eighths of the project will be completed. How many days will it take for the two teams to complete the project independently?

1. Distance = 48 * 5 = 240 (km)
Return speed = 48 * (1 / 6) = 8 (km / h)
Return time = 240 / 8 = 30 (hours)
Round trip time = 5 + 30 = 35 (hours)
2. If the velocity of a is a and the velocity of B is B, there are two formulas
(1) Quantity = (a + b) * 10
(2) 3 / 8 quantity = 3A + 4B
Combining the two formulas, we can get b = 3A
By substituting (1), we can get the following result: quantity = 40A
So a's time = quantity / a = 40A / a = 40 (days)
B time = quantity / b = 40A / 3A = 40 / 3 = (approximately equal to) 14 (days)

1.2÷3/2÷4/3÷5/4.÷100/99=?
2.2010×2009/2008
3. A basket of fresh peaches, less than 60, will be given to four monkeys, namely, a, B, C and D. monkey a will get 7 / 2, B 3 / 1 and C 14 / 5 of the total number of peaches, and the rest will be given to D and D. how many peaches will be given?
4. A woman was washing dishes by the river. The officer in charge of the river passed by and asked, "how can you wash so many dishes?" the woman answered, "there are guests at home." the officer asked, "how many guests are there?" the woman answered, "two people share a rice bowl, three people share a rice bowl, four people share a rice bowl, a total of 65 bowls." how many people are there in all?

I did the third question only to find that your score should be wrong
Do you want to say 2 divided by 2 / 3 divided by 3 / 4
1. Dividing by a fraction is equal to multiplying by the reciprocal of the fraction. For example, 2 ﹣ 3 / 2 ﹣ 4 / 3 = 2 * 2 / 3 * 3 / 4. The denominator of the numerator and the previous fraction can be divided approximately, and so on. Finally, it can be worked out. According to your question, I get one in 25
2. Connect 20102009 with 2008. 2010 = 2008 + 22009 = 2008 + 1
2010*2009/2008=（2008+2）*（2008+1）/2008=（2008*2008+3*2008+2）=2011+1/1004
3. I can only use 2 / 7, 1 / 3, 14 / 5 to calculate this. The idea is that the peach can not be divided into half, it must be one, then the total number of peaches must be divisible by 7, 3, 14, and no more than 60. So it should be 42 peaches. Then, Ding should get one peach
4. There should be 60 people. This number should be divisible by 2,3,4. Since there are 65 bowls in total, the mantissa of 5 can be obtained by dividing the number by 3. (because 2,4, multiplied by any number is even, no 5 can be obtained). The least common multiple of 2,3,4,5 is 60. 60 people. If every two people share a bowl, then there are 30 bowls, and every three people share 20 bowls, Every four people share 15 bowls, just 65 bowls
I don't know if you can read it

3 red chopsticks, 9 yellow chopsticks, 18 green chopsticks, 2 white chopsticks and 1 Black chopsticks. At least how many chopsticks can be touched to ensure the safety of chopsticks
Two pairs of chopsticks of the same color

Touch at least 13 chopsticks to ensure 2 pairs of chopsticks of the same color
Considering the opposite situation, no two pairs of chopsticks with the same color can be found. How many chopsticks can you take out in this situation
That is, 3 red + 3 Yellow + 3 green + 2 white + 1 Black = 12 chopsticks
If you smoke one more, there will be two pairs of chopsticks of the same color,
So make sure that 2 pairs of chopsticks of the same color are at least 13