Explicação passo-a-passo:
[tex] \frac{7}{1} \div \frac{1}{3} = \frac{7}{1} \times \frac{3}{1} = \frac{21}{1} = 21 \\ \\ \frac{2}{5} \div \frac{6}{7} = \frac{2}{5} \times \frac{7}{6} = \frac{14}{30} \div \frac{2}{2} = \frac{7}{15} \\ \\ \frac{2}{8} \div \frac{6}{1} = \frac{2}{8} \times \frac{1}{6} = \frac{2}{48} \div \frac{2}{2} = \frac{1}{24} \\ \\ \frac{8}{5} \div \frac{2}{15} = \frac{8}{5} \times \frac{15}{2} = \frac{120}{10} \div \frac{10}{10} = \frac{12}{1} = 12[/tex]
