a) [tex]2\frac{3}{4} + 1\frac{3}{5} = \frac{11}{4} + \frac{8}{5} = \frac{55}{20} + \frac{32}{20} = \frac{87}{20} = 4\frac{7}{20}[/tex]
[tex]3\frac{1}{6} - 1\frac{4}{9} = \frac{19}{6} - \frac{13}{9} = \frac{57}{18} - \frac{26}{18} = \frac{31}{18} = 1\frac{13}{18}[/tex]
b) [tex]3\frac{1}{5} - 2\frac{4}{5} + 1\frac{3}{5} = \frac{16}{5} - \frac{14}{5} + \frac{8}{5} = \frac{10}{5} = 2[/tex]
[tex]2\frac{3}{4} + 3\frac{5}{6} - 4\frac{2}{3} = \frac{11}{4} + \frac{23}{6} - \frac{14}{3} = \frac{33}{12} + \frac{46}{12} - \frac{56}{12} = \frac{23}{12} = 1\frac{11}{12}[/tex]
