3 4/5 +1 4/5 ;1 4/5 +7 7/18 ; 8 4/5 + 2 1/3 ; 12 5/6 +4/15 ; 7/20 +2 7/10; 8 3/7 +1 9/14

[latex]3 frac{4}{5} +1 frac{4}{5}=5 frac{3}{5}[/latex] [latex]1frac{4}{5} +7frac{7}{18} =frac{9}{5} +frac{133}{18} =frac{9*18+133*5}{90} =frac{827}{90}=9frac{17}{90}[/latex]   [latex]8frac{4}{5} + 2frac{1}{3}=frac{44}{5} +frac{7}{3}=frac{44*3+7*5}{15}=frac{167}{15}=11frac{2}{15}[/latex]  [latex]12frac{5}{6}+frac{4}{15}=frac{77}{6}+frac{4}{15}=frac{77*5+4*2}{30}=frac{393}{30}=13frac{3}{30}=13frac{1}{10}[/latex]  [latex]frac{7}{20}+2frac{7}{10}=frac{7}{20}+frac{27}{10}=frac{7+27*2}{20}=frac{61}{20}=3frac{1}{20}[/latex] [latex]8frac{3}{7} +1frac{9}{14}=frac{59}{7}+frac{23}{14}=frac{59*2+23}{14}=frac{141}{14}=10frac{1}{14}[/latex]