[tex]10\dfrac{1}{2}+5\dfrac{1}{4}=10\dfrac{2}{4}+5\dfrac{1}{4} = 15\dfrac{3}{4}[/tex]
[tex]8\dfrac{3}{5}-1\dfrac{3}{5}=8\dfrac{12}{20}-1\dfrac{15}{20} = 7\dfrac{32}{20} -1\dfrac{15}{20} = 6\dfrac{17}{20}[/tex]
[tex]2\dfrac{1}{5}\times 3\dfrac{1}{4} =\dfrac{11}{5}\times\dfrac{13}{4} =\dfrac{143}{20} = 7\dfrac{3}{20}[/tex]
[tex]1\dfrac{1}{7}:1\dfrac{1}{9} = \dfrac{8}{7}:\dfrac{10}{9} = \dfrac{8}{7}\times\dfrac{9}{10} = \dfrac{4}{7}\times\dfrac{9}{5} = \dfrac{36}{35} = 1\dfrac{1}{35}[/tex]
