1 3/4+ 2 1/3 - (1 1/6 - 1/2) / полоска тема дробей

1 3/4=7/4
2 1/3=7/3
1 1/6=7/6
1)7/6-1/2=7/6-3/6=4/6
2)7/4+7/3=7/7
3)7/7-4/6=42/42-28/42=14/42=1/3