6:2/7=6·7/2=3·7=21
1:8/19=1·19/8=19/8=2 3/8
7/25:28=7/25·1/28=1/100
16 1/3:5 5/6=49/3·6/35=7/1·2/5=14/5=2 4/5
2 2/3:2 2/7=8/3·7/16=1/3·7/2=7/6=1 1/6
4 4/9:5/27=40/9·27/5=8/1·3/1=24
(8 5/7-6 5/6:1 5/36):4 3/4=4/7
6 5/6:1 5/36=41/6·36/41=1·6=6
8 5/7-6=2 5/7
2 5/7:4 3/4=19/7·4/19=1/7·4/1=4/7