2целых 2/5-(1/4+7/10)=
2целых 2/5-(1/4+7/10)=12/5-(5/20+14/20)= 12/5-19/20=48/20-19/20=29/20=1 9/20
2 2/5-(5/20+14/20)=1 28/20-19/20=1 целая 9/20