1)-5/1282 2/3-7 2/3*(-1/6)=-5/12*8/3+23/3*1/6=-10/9+23/18=-20/18+23/18=3/18=1/6
2)(-3/5*0,8-13/25)*0,7=(-3/5*8/10-13/25)*0,7=(-24/50-13/25)*0,7=(-24/50-26/50)*0,7=-50/50*0,7=-1*0,7=-0,7
3)(-1 3/7*4 2/3+1 7/9)*(-3/4)=(-10/7*14/3+16/9)*(-3/4)=(-20/3+16/9)*(-3/4)=(-60/9+16/9)*(-3/4)=(-44/9)*(-3/4)=11/3=3 2/3