you can make them have the same denominator and then compare
[tex]( \frac{3}{4}) ( \frac{16}{16}) = \frac{48}{64} [/tex]
[tex] (\frac{11}{16})( \frac{4}{4}) = \frac{44}{64} [/tex]
so as you can see, [tex] \frac{3}{4} is \frac{4}{64} bigger than \frac{11}{16} [/tex]
