Răspuns:
5/9-4/9=1/9
6/10-4/10=2/10
5/8-3/8=2/8
5/7-2/7=3/7
1. 5/9 si 4/9
2. 6/10 si 4/10
3. 5/8 si 3/8
4. 5/7 si 2/7