a)
[tex]\frac{7-2}{9} \\= \frac{5}{9}[/tex]
b)
[tex]\frac{17}{12} - \frac{1}{12} \\= \frac{4}{3}\\= 1\frac{1}{3}[/tex]
c)
[tex]4+\frac{2}{5} -3\\(4-3)+\frac{2}{5} \\1+\frac{2}{5} \\= 1\frac{2}{5}[/tex]
d)
[tex](6-2)+(\frac{6}{7} -\frac{4}{7})\\4+\frac{2}{7}\\= 4\frac{2}{7}[/tex]
