a)
[tex]\frac{64}{5} - (\frac{17}{5}-\frac{4}{5} )\\\\\frac{64}{5} -\frac{13}{5} \\\\\frac{51}{5} = 10\frac{1}{5}[/tex]
b)
[tex]\frac{77}{9} -\frac{25}{9} -(3+\frac{12}{9})\\ \\\frac{52}{9} -(3+1\frac{3}{9})\\\\\frac{52}{9} - \frac{39}{9} =\frac{13}{9} =1\frac{4}{9}[/tex]
