54% is 54 out of 100.
There for the numerator is 54 and the denominator is 100.
[tex] \frac{54}{100} [/tex]
Now, both the top and the bottom can be divided by 2. So:
[tex] \frac{54~divided~by~2}{100~divided~by~2} [/tex] = [tex] \frac{27}{50} [/tex]
[tex] \frac{27}{50} [/tex] can't be simplified anymore, therefore, 27/50 is 54% as a fraction.
~Hope this helped :)