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To build an expressway, 260 meters a day, the total length will be extended by 8 days, 300 meters a day, and the total length will be extended by 4 days. How long is this road?
This road is 7800 meters long.

Interpretation and analysis: the number of days scheduled to complete the task in the question is equivalent to "the total number of people participating in the distribution". According to the quantitative relationship of "total number of people participating in distribution = (big loss-small loss) ÷ distribution difference", we can know that:

The original number of days to complete the task is:

(260× 8-300× 4) ÷ (300-260) = 22 (days)?

The total length of this road is 300× (22+4) = 7800 meters?

The total length of this road is 7800 meters.

Extended data:

In daily life, do one thing, make a product, complete a task, complete a project, etc. , all involve the total amount of work, work efficiency and working hours. The basic quantitative relationship between them is-work efficiency × time = total amount of work.

In primary school mathematics, we all call it "engineering problem", and discuss the relationship between these three quantities.

Give a simple example: A work can be completed in 15 days, and B work can be completed in 10 days. How many days can two people cooperate to complete it?

As a whole, an assignment is 1, so the workload can be counted as 1. The so-called work efficiency is the amount of work completed in a unit time. The time unit we use is "day", and 1 day is a unit.

According to the basic quantitative relationship, it is concluded that workload ÷ work efficiency = working time;

1÷( 1/ 15+ 1/ 10)

=6 (days)

A: It takes six days for two people to cooperate.