Since 3/sqrt(3) has a radical in its denominator, you must do a process known as rationalization. Rationalization is when you must multiply the whole fraction by another fraction where the numerator and denominator are sqrt(3). By doing so, you remove the radical, since sqrt(3) (1.7320508...) is irrational, that is, the decimal goes on forever without repeating.
3/sqrt(3)color(red)(*sqrt(3)/sqrt(3))
=(3color(red)(*sqrt(3)))/(sqrt(3)color(red)(*sqrt(3)))
=(3sqrt(3))/3
Notice how once you rationalize the fraction, the denominator is not irrational anymore. Also, keep in mind that you did not change the value of the simplified fraction. Since sqrt(3)/sqrt(3) is equal to 1, you simply rearranged the way it was written. The value of the simplified fraction stays the same.
