1. 1600:80+t=60
20+t=60
t=60-20
t=40
2. (2000-600):f=70
1400:f=70
f=1400:70
f=20
3. d-(1300-678)=400
d-622=400
d=400+622
d=1022
1600/800+t=60
2+t=60
t=60-2
t=58
(2000-600)/f=70
1400/f=70
f=1400/70
в-(1300-678)=400
в-622=400
в=400+622
в=1022
