In a week, there are two legal rest days (Saturday and Sunday) and five working days (Monday to Friday), so in a week, rest days are working days: 2 ÷ 5 = 2/5.

Extended data:

Precautions:

1, the working day is wrongly written as the number of days in a week. For example, this problem can easily be wrongly written as two-sevenths, which is an error-prone point.

2. The order of numerator and denominator. For example, the rest day is the fraction of the working day, the denominator is the working day and the numerator is the rest day.

In a week, the legal rest days in China are two days. Since the Han Dynasty, officials have been required to have a rest every five days.