\((\frac{1}{0.06} \div \frac{1}{0.042})^{-1}\) = \((\frac{100}{6} \div \frac{1000}{42})^{-1}\) = \((\frac{100}{6} \times \frac{42}{1000})^{-1}\) = \((\frac{7}{10})^{-1}\) = \(\frac{10}{7}\) = 1.4285 \(\approxeq\) 1.43.