(4/15-3/10):1 целая 3/40 +(-2целых 4/19)*(1/3+4/7)=1 5/129
1. 4/15-3/10=8/30-9/30=-1/30
2.-1/30:1 3/40=-1/30*40/43=-4/129
3. 1/3+4/7=7/21+12/21=19/21
4.-2 4/19*19/21=-42/19*19/21=-2
5.-4/129+2=1 129/129-4/129=1 5/129
