1) 1 1/3:4/5 2) 3-2 5/7= 3) 30×5/6= "/"-означает дробь.

Ответ:

1. $1 \frac{1}{3}: \frac{4}{5} =\frac{1*3+1}{3}:\frac{4}{5}=\frac{4}{3}:\frac{4}{5}=\frac{4}{3} *\frac{5}{4} =\frac{4*5}{3*4} =\frac{20}{12} =\frac{5*4}{3*4}=\frac{5}{3} =1\frac{2}{3}$

2. $3 - 2 \frac{5}{7} =\frac{3}{1} - 2 \frac{5}{7} =\frac{3}{1}-\frac{2*7+5}{7}=\frac{3}{1}-\frac{19}{7} =\frac{7*3}{7*1}-\frac{1*19}{1*7} =\frac{21}{7} -\frac{19}{7} =\frac{21-19}{7} =\frac{2}{7}$