12 3/5-7 1/6+2 3/10=
4/5:2 2/3+3 1/2=
170 8/51-2 4/9:3 2/3=

$12 frac{3}{5} -7 frac{1}{6} +2 frac{3}{10} =12 frac{18}{30} -7 frac{5}{30} +2 frac{9}{30}=7 frac{22}{30} =7 frac{11}{15}$

$frac{4}{5} :2 frac{2}{3} +3 frac{1}{2}= frac{4}{5} : frac{8}{3} +3 frac{1}{2}= frac{4}{5} * frac{3}{8} +3 frac{1}{2}= frac{3}{10} +3 frac{1}{2}=frac{3}{10} +3 frac{5}{10}=3 frac{8}{10} =$
$=3 frac{4}{5}$

$170 frac{8}{51} -2 frac{4}{9}:3 frac{2}{3} =170 frac{8}{51} - frac{22}{9}: frac{11}{3}=170 frac{8}{51} - frac{22}{9}*frac{3}{11}=170 frac{8}{51} - frac{2}{3}=$
$=170 frac{8}{51} - frac{34}{51}=169 frac{59}{51} - frac{34}{51}=169frac{25}{51}$