To expand or to cancel a fraction, you have to multiply / divide the numerator
as well as the denominator
of the fraction with the same number.
What does it mean to cancel a fraction?
It means that you divide the numerator and the denominator of the fraction by the same number. This makes the fraction better understandable.
Can a fraction be cancelled infinite times?
No. This is only possible as long as numerator and denominator have no common divisors. To cancel a fraction as far as possible immediately, cancel by the greatest common divisor of the numerator and the denominator.