ответ:

[tex]\displaystyle \frac{89}{30}=2\frac{29}{30}[/tex]

решение:

[tex]\displaystyle 3:3\frac{3}{4}+2\frac{2}{5}*2\frac{1}{2}-3\frac{5}{6}=3:\frac{15}{4}+2\frac{2}{5}*2\frac{1}{2}-3\frac{5}{6}=3:\frac{15}{4}+\frac{12}{5}*2\frac{1}{2}-3\frac{5}{6}=\\\\3:\frac{15}{4}+\frac{12}{5}*\frac{5}{2}-3\frac{5}{6}=3:\frac{15}{4}+\frac{12}{5}*\frac{5}{2}-\frac{23}{6}=3*\frac{4}{15}+\frac{12}{5}*\frac{5}{2}-\frac{23}{6}=\\\\3*\frac{4}{15}+12*\frac{1}{2}-\frac{23}{6}=3*\frac{4}{15}+6-\frac{23}{6}=\frac{4}{5}+6-\frac{23}{6}=\frac{89}{30}=2\frac{29}{30}[/tex]