The school distributed 300 books to three classes in grade six. One class gave a quarter, the other two classes gave two fifths and the rest gave three classes. How many books were given to three classes? Class three was assigned 105 books.

Solution: Because the total number of books is 300,

Then a quarter of the books are equal to 300x 1/4=75.

Two fifths of the books are equal to 300x2/5= 120.

Then the remaining books are equal to 300-75- 120= 105.

That is to say, 105 books were distributed to three classes.

Multiplication rule of fractions

The (1) score is multiplied by an integer, the denominator remains the same, and the numerator is multiplied by an integer as a new numerator, which can finally be simplified into an offer score.

(2) Fraction multiplied by fraction, numerator multiplied by numerator as new numerator, denominator multiplied by denominator as new denominator, and finally points that can be reduced are given.

Calculation formula of subtraction

Subtraction-subtraction = difference;

Subtraction-difference = subtraction;

Subtraction+difference = minuend.