Răspuns:
28.
a) x=8 y=3
8............3
12(x)........y y=12×3/8=36:8=4,5
b)8..........3
2..........y y=2×3/8=0,75
c)8...........3
x.........30 x=8×30/3=80
d)8...........3
x..........0.9 x=8×0.9/3=7,2/3=2,4
29.
a)u=12 v=20
12...........20(v)
5..............v(20) v=20×12/5=240/5=48
b)12..........20(v)
8................v(20) v=20×12/8=240/8=30
c)12...........20(60)
u.................60(20) u=12×20/60=240/60=40
d)12......20(3)
u............3(20) u=12×20/3=240/3=80
