7-3/5+2целых 7/9; 9+1целая 3/4-2/5; 6 целых 5/9+3-7/12. Помогите пожалуйста .

1) $7- \frac{3}{5} +2 \frac{7}{9}$
$7=6 \frac{5}{5}$
$6 \frac{5}{5} - \frac{3}{5} =6 \frac{2}{5}$
$6 \frac{2}{5} +2 \frac{7}{9} =8 \frac{2*9+7*5}{45} =8 \frac{53}{45} =9 \frac{8}{45}$
2) $9+1 \frac{3}{4} - \frac{2}{5}$
$9+1 \frac{3}{4} =10 \frac{3}{4}$
$10 \frac{3}{4} - \frac{2}{5} = \frac{43}{4} - \frac{2}{5} = \frac{5*43}{5*4} - \frac{2*4}{5*4} = \frac{215-8}{20} = \frac{207}{20}=10 \frac{7}{y20}$
3) $6 \frac{5}{9} +3- \frac{7}{12}$
$6 \frac{5}{9} +3=9 \frac{5}{9}$
$9 \frac{5}{9} - \frac{7}{12} = \frac{9*9+5}{9} - \frac{7}{12} = \frac{86}{9} - \frac{7}{12}$ ]
$\frac{4*86}{4*9} - \frac{3*7}{3*12} = \frac{344}{36} - \frac{21}{36} = \frac{344-21}{36} = \frac{323}{36} =8 \frac{35}{36}$