A teacher's school day is 81/4 h long. The teacher has six classes everyday. Each class is 5/6 h long. About how many hours of the school day is the teacher not in class?

8 1/4 - (5/6 * 6 ) =

To find out how many hours of the school day the teacher is not in class, we need to subtract the total time in class from the length of the school day.

The teacher has six classes every day, and each class is 5/6 hours long. Therefore, the total time in class can be calculated by multiplying the length of one class by the number of classes:

Total time in class = (5/6 hours/class) * (6 classes) = 5 hours

The school day is 8 1/4 hours long. To find out how many hours the teacher is not in class, we subtract the total time in class from the length of the school day:

Time not in class = (8 1/4 hours) - (5 hours)

First, we need to convert 8 1/4 to an improper fraction.
8 1/4 = (4 * 8 + 1) / 4 = 33/4

Time not in class = 33/4 hours - 5 hours

Now, we need to subtract the fractions:

Time not in class = 33/4 hours - 20/4 hours

To subtract the fractions, we need a common denominator:

Time not in class = (33 - 20) / 4 hours

Time not in class = 13/4 hours

Therefore, the teacher is not in class for approximately 13/4 hours of the school day.