a)3 3/42 2/5-4 3/8 =
3\frac{3}{4}*2\frac{2}{5}-4\frac{3}{8}=\frac{15}{4}*\frac{12}{5}-4\frac{3}{8}=\frac{3}{1}*\frac{3}{1}-4\frac{3}{8}=9-4\frac{3}{8}=8\frac{8}{8}-4\frac{3}{8}=4\frac{5}{8}
b)
10-1 1/64 1/2 =
10-1\frac{1}{6}*4\frac{1}{2}=10-\frac{7}{6}*\frac{9}{2}=10-\frac{7}{3}*\frac{3}{2}=10-\frac{21}{6}=\frac{60}{6}-\frac{21}{6}=\frac{39}{6}=6\frac{3}{6}=6\frac{1}{2}=6,5
c)
5/7*4 2/3+5/6: 1 1/9 =
\frac{5}{7}*4\frac{2}{3}+\frac{5}{6}:1\frac{1}{9}=\frac{5}{7}*\frac{14}{3}+\frac{5}{6}:\frac{10}{9}=\frac{5}{1}*\frac{2}{3}+\frac{5}{3}:\frac{5}{9}=\frac{10}{3}+\frac{5}{6}*\frac{9}{10}=
\frac{10}{3}+\frac{1}{2}*\frac{3}{2}=\frac{10}{3}+\frac{3}{4}=\frac{40+9}{12}=\frac{49}{12}=4\frac{1}{12}
d)(2 1/4-1 2/3):(1/6+2/9) =
(2\frac{1}{4}-1\frac{2}{3}):(\frac{1}{6}+\frac{2}{9})=(\frac{9}{4}-\frac{5}{3}):(\frac{3}{18}+\frac{4}{18})=(\frac{27}{12}-\frac{20}{12}):\frac{7}{18}=\frac{7}{12}*\frac{18}{7}=\frac{3}{2}=1\frac{1}{2}=1,5