Răspuns:
[tex]1, (7)=\frac{17-1}{9} =\frac{16}{9}[/tex]
[tex]2,(7)=\frac{27-2}{9} = \frac{25}{9}[/tex]
[tex]3,(7) = \frac{37-3}{9} = \frac{34}{9}[/tex]
[tex]\frac{16}{9} +\frac{25}{9} +\frac{34}{9} = \frac{16+25+34}{9} =\frac{75}{9} = \frac{25}{3}[/tex]