Ответ:
Пошаговое объяснение:
1)= (9 1/9a+1/3a)-(20c-18.1c)=(9 1/9a+3/9a)-1.9c=12 4/9a-1.9c
2) = 6.5х-7.1х+8.25х-19=7.65х-19
3)=(-1.6у-3у+2 3/7y)+2.6=(-4 3/5y+2 3/7y)+2.6=(-4 21/35y+2 15/35y)+2.6=
-2 6/35y+2.6
4)=(-4 1/6z+5.5z)-(3c-2 1/3c)=(-4 1/6z+5 3/6z)-2/3c=1 1/3z-2/3c