(b) \(\frac{13}{15}\)
\(\frac{1}{1+\frac{\frac23}{1+\frac23+\frac{\frac89}{1-\frac23}}}\) = \(\frac{1}{1+\frac{\frac23}{1+\frac23+\frac{\frac89}{\frac13}}}\)
= \(\frac{1}{1+\frac{\frac23}{1+\frac23+\frac83}}\) = \(\frac{1}{1+\frac{\frac23}{\frac{13}{3}}}\)
= \(\frac{1}{1+\frac{2}{13}} = \frac{1}{\frac{15}{13}}\) = \(\frac{13}{15}.\)