А)(1600+t) : 80 = 60
1600 + t = 4800
t = 4800 - 1600
t = 3200
2000:f - 670 = 1330
2000 = 670f + 1330f
2000 = 2000f
f = 1
1300 - (d-678) = 400
1300 - d + 676 = 400
-d = -1300 - 676 + 400
-d = -1576
d = 1576
б) 1600:80 +t = 60
1600 + 80 t = 4800
80t = 4800 - 1600
80t = 3200
t = 40
(2000-600) :f = 70
1400 = 70f
f = 20
d - (1300-678) = 400
d - 622 = 400
d = 400 + 622
d = 1022