A manuscript of 60 pages, originally planned to finish in 5 hours, only 4 hours, work efficiency increased by several percent? This problem has caused controversy in our class. Will the final result be 20% or 25%, please give us the reasons or the formula,

A manuscript of 60 pages, originally planned to finish in 5 hours, only 4 hours, work efficiency increased by several percent? This problem has caused controversy in our class. Will the final result be 20% or 25%, please give us the reasons or the formula,

Original efficiency: 20%
Current efficiency: 25%
（25％－20％）/20％
＝25％

The typist prints a manuscript, originally planned to finish it in 4 hours, but finished it in 3 hours. How much has the work efficiency been improved?

Original efficiency 1 / 4
Current efficiency 1 / 3
Improve the efficiency of typists: (1 / 3-1 / 4) / (1 / 4) * 100% ≈ 33.3%

Volunteer a plans to complete a certain work in the community in several working days. From the third working day, volunteer B will join the work, and
If Party A and Party B have the same work efficiency and complete the task 3 days in advance, the number of days Party A plans to complete the work is

In fact, this problem is very simple: 2 + 3 + 3 is the answer
Because the work efficiency is the same, the total time of two manual actions is the time that a person needs. If a person does it, the time required is divided into three parts: one is to do it for two days, the other is to work with B, and the third is to work three days in advance. As long as the time of simultaneous work is solved, it is OK. The time of simultaneous work is also the time that B works, because the work efficiency wants to be the same, The number of days of day B is the number of days in advance of day a is 3 days
So the number of days a needs to do it alone is
2 + 3 + 3 = 8 days
If you use the equation,
Let a be x days,
2+（x-2-3）*2=x
x=8
There's no need to use grades, because pupils may not have learned them yet
The way of thinking of the equation, or to grasp the work of the same sentence
X-2-3 is the time for two people to work together. If a is allowed to work alone, the number of days used must be multiplied by 2
I agree with you. Let's see the solution

Volunteer a plans to complete a certain work in the community in several working days. From the third working day, volunteer B joins in the work, and the work efficiency of both Party A and Party B is the same. As a result, the task is completed 3 days in advance, the number of days that volunteer a plans to complete the work is ()
A. 8B. 7C. 6D. 5

Suppose volunteer a plans to complete this work in X days, so the work efficiency of both Party A and Party B is: 1 x, Party A has completed 1 x × 2 in the first two working days, and has completed 1 x (x − 2 − 3) and 1 x (x − 2 − 3) in the remaining working days, then 2x + 2 (x − 2 − 3) x = 1, and the solution is x = 8