a)
[tex]2\frac{3}{20}+\frac{1}{4} = 2\frac{3}{20}+\frac{5}{20} = 2\frac{8}{20} = 2\frac{2}{5}\\\\\\1\frac{5}{18}+2\frac{4}{9} + \frac{5}{6} = 1\frac{5}{18}+2\frac{8}{18}+\frac{15}{18} =3\frac{28}{18} = 4\frac{10}{18} = 4\frac{5}{9}\\\\\\3\frac{1}{2}+2\frac{3}{4}+1\frac{1}{3} = 3\frac{6}{12}+2\frac{9}{12} + 1\frac{4}{12}}=6\fracP19}{12} = 7\frac{7}{12}[/tex]
b)
[tex]2\frac{1}{20}-\frac{3}{4} - 1\frac{21}{20} - \frac{15}{20} =1\frac{6}{20} = 1\frac{3}{10}\\\\\\1\frac{7}{18}-2\frac{2}{9} = 1\frac{7}{18}-2\frac{4}{18} = 1\frac{7}{18}-1\frac{22}{18} = -\frac{15}{18} = -\frac{5}{6}\\\\\\2\frac{1}{7}-5\frac{2}{3} = 2\frac{7}{21} -5\frac{14}{21} = -3\frac{7}{21} = -3\frac{1}{3}[/tex]
