Решите уравнения: а) (1600+t) : 80 = 60 б) 1600: 80 +t = 60 2000: f - 670 = 1330 (2000-600) : f = 70 1300 - (d-678) = 400 d - (1300-678) = 400 надо

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