remember [tex]x^ \frac{m}{n}= \sqrt[n]{x^m} [/tex]
so
simplify each seperately
[tex]27^ \frac{2}{3}= \sqrt[3]{27^2} = \sqrt[3]{729}=9 [/tex]
[tex]\frac{1}{8}^ \frac{2}{3}= \sqrt[3]{\frac{1}{8}^1} = \sqrt[3]{\frac{1}{8}}=\frac{1}{2} [/tex]
so we now have
9-1/2=8.5
