[tex] \frac{7}{9} + \frac{1}{9} = \frac{8}{9} [/tex]
[tex] \frac{4}{9} \times 9 = 4[/tex]
[tex] \frac{4}{7} + \frac{5}{14} = \frac{8}{14} + \frac{5}{14} = \frac{13}{14} [/tex]
[tex] \frac{4}{7} \times \frac{5}{12} = \frac{5}{21} [/tex]
[tex] \frac{13}{19} - \frac{7}{19} = \frac{6}{19} [/tex]
[tex] \frac{12}{17} \div 3 = \frac{12}{17} \times \frac{1}{3} = \frac{4}{17} [/tex]
[tex] \frac{2}{3} - \frac{1}{5} = \frac{10}{15} - \frac{3}{15} = \frac{7}{15} [/tex]
[tex] \frac{4}{9} \div \frac{5}{9} = \frac{4}{9} \times \frac{9}{5} = \frac{4}{5} [/tex]