You may have combined the numerators and then added the denominators. Instead, find the least common denominator and use this to rewrite each term as an equivalent fraction:

$\displaystyle\frac{{{6}{x}}}{{{{x}}^{{2}}-{64}}}-\frac{{8}}{{{4}{x}-{32}}}+\frac{{2}}{{{x}+{8}}}=\frac{{{6}{x}{\left({4}\right)}}}{{{4}{\left({x}-{8}\right)}{\left({x}+{8}\right)}}}-\frac{{{8}{\left({x}+{8}\right)}}}{{{4}{\left({x}-{8}\right)}{\left({x}+{8}\right)}}}+\frac{{{2}{\left({4}\right)}{\left({x}-{8}\right)}}}{{{4}{\left({x}-{8}\right)}{\left({x}+{8}\right)}}}\usepackage{cmbright}\Huge\$

Then simplify and combine the numerators.