(3/4-4/5)*7,8+(2/3+4/7)*7/13=83/300
3/4-4/5=15/20-16/20=-1/20
-1/20*7,8=-0,05*7,8=-0,39
2/3+4/7=14/21+12/21=26/21
26/21*7/13=2/3
-0,39+2/3=-39/100+2/3=83/300
(3/4-4/5)*7,8+(2/3+4/7)*7/13=83/300
3/4-4/5=15/20-16/20=-1/20
-1/20*7,8=-0,05*7,8=-0,39
2/3+4/7=14/21+12/21=26/21
26/21*7/13=2/3
-0,39+2/3=-39/100+2/3=83/300