\(\frac{1}{3} \div [\frac{5}{7}(\frac{9}{10} -1 + \frac{3}{4})]\)
\(\frac{1}{3} \div [\frac{5}{7}(\frac{9}{10} - \frac{10}{10} + \frac{3}{4})]\)
= \(\frac{1}{3} \div [\frac{5}{7}(\frac{-1}{10} + \frac{3}{4})]\)
= \(\frac{1}{3} \div [\frac{5}{7}(\frac{-2 + 15}{20})]\)
= \(\frac{1}{3} \div [\frac{5}{7} \times \frac{13}{20}]\)
\(\frac{1}{3} + [\frac{13}{28}]\) = \(\frac{1}{3} \times \frac{28}{13}\)
= \(\frac{28}{39}\)