(12 5/12+1 2/3-3 5/6+2 3/4):(2 1/2*2/5-7/9)

[tex](12 \frac{5}{12} +1 \frac{2}{3} -3 \frac{5}{6} +2 \frac{3}{4} ):(2 \frac{1}{2}\cdot \frac{2}{5} - \frac{7}{9} )= \\ \\ = (12 \frac{12}{12} ):( \frac{5}{2}\cdot \frac{2}{5} - \frac{7}{9} )= (13):(1 - \frac{7}{9} )= (13):( \frac{9}{9} - \frac{7}{9} )= \\ \\ =(13):(\frac{2}{9} )=13\cdot \frac{9}{2}=\frac{117}{2} =58\frac{1}{2} [/tex]

По действиям:

[tex]1)(12 \frac{5}{12} +1 \frac{2}{3} -3 \frac{5}{6} +2 \frac{3}{4} )=12 \frac{12}{12}=13 \\ \\ 2)(2 \frac{1}{2}\cdot \frac{2}{5} - \frac{7}{9} )= \frac{5}{2}\cdot \frac{2}{5} - \frac{7}{9} = 1 - \frac{7}{9} = \frac{9}{9} - \frac{7}{9} =\frac{2}{9} \\ \\ 3)13: \frac{2}{9}= 13\cdot \frac{9}{2}=\frac{117}{2} =58\frac{1}{2} [/tex]