A fraction is expressed in lowest terms (or simplest form) when it is reduced.
A fraction is reduced when the greatest common factor of the numerator and denominator is one.
The greatest common factor of six and eight is two. Dividing both the numerator and denominator by two yields the following:
The greatest common factor of twenty and eight is four. Dividing both the numerator and denominator by four yields the following:
The greatest common factor of fifteen and twenty is five. Dividing both the numerator and denominator by five yields the following: