A: [tex]6 \frac{8}{9} - \frac{2}{3} = 6 \frac{8}{9} - \frac{6}{9} = 6 \frac{2}{9}[/tex]
B: [tex]6 \frac{1}{4} - \frac{5}{8} =6 \frac{2}{8} - \frac{5}{8} = 5 \frac{10}{8} - \frac{5}{8} =5 \frac{5}{8}[/tex]
C: [tex]1 \frac{1}{2} - \frac{6}{7} = \frac{3}{2} - \frac{6}{7} = \frac{21}{14} - \frac{12}{14} = \frac{9}{14}[/tex]
D: [tex]7 \frac{3}{4} - 4\frac{5}{6} = 7 \frac{9}{12} - 4 \frac{10}{12} = 6 \frac{21}{12} - 4 \frac{10}{12} = 2 \frac{11}{12}[/tex]
