3)
[tex] \frac{3}{7} + x = \frac{9}{7} \\ \ x = \frac{9}{7} - \frac{3}{7} \\ x = \frac{6}{7} [/tex]
[tex] \frac{3}{5} + x = \frac{7}{5} \\ x = \frac{7}{5} - \frac{3}{5} \\ x = \frac{4}{5} [/tex]
[tex] \frac{11}{16} + \frac{2}{16} + x = \frac{16}{16} \\ \frac{13}{16} + x = \frac{16}{16} \\ x = \frac{16}{16} - \frac{13}{16} \\ x = \frac{3}{16} [/tex]
[tex]x + \frac{8}{25} + \frac{7}{25} = 1 \\ x + \frac{15}{25} = 1 \\ x = 0[/tex]
