3 : 1/9
4/9:8/9
3/5:1/25
1/10:1/10

3 : 1/9 = 3 · 9/1 = 274/9:8/9 = 4/9 ·9/8 = 4/1 · 1/8 = 1/23/5:1/25 = 3/5 · 25/1 = 3 · 5 =151/10:1/10 = 1/10 · 10/1 = 1