[tex]Aby\ odjac\ lub\ dodac\ ulamki\ o\ roznych\ mianownikach , \\ nalezy\ sprowadzic\ je\ do \ wspolnego\ mianownika \\\\a)\\\\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\frac{19}{12}=7\frac{7}{12}[/tex]
[tex]b)\\\\2\frac{1}{20}-\frac{3}{4}= 2\frac{1}{20}-\frac{15}{20}=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{3}{21}-5\frac{14}{21}=-3\frac{11}{21}[/tex]
