[tex]( \frac{19}{45} \div \frac{7}{30}) \div \frac{19}{21} = \\ ( \frac{19}{45} \times \frac{30}{7} ) \div \frac{19}{21} = \\ \frac{570}{315} \times \frac{21}{19} = ( 570cu \: 19. \: 315cu \: 21) = \\ \frac{30}{15} = \frac{2}{1} = 2[/tex]
[tex]( \frac{13}{12} \div \frac{7}{15} ) \div \frac{39}{70} = \\ ( \frac{13}{12} \times \frac{15}{7} ) \div \frac{39}{70} = \\ \frac{195}{84} \times \frac{70}{39} = (simplific195cu39) \\ \frac{350}{84}^{(14} = \frac{25}{6}[/tex]
