Дроби к общему знаменателю: 3/10 и 2/3 4/5 и 4/9 1/2 и 1/7 5/8 и 7/11 4/25 и 9/10 5/6 и 4/9 3/20 и 2/15 3/4 и 9/10 3/9 и 15/25 4/6 и 6/8 2/4 и 6/9 21/98 и 20/84

3/10 и 2/3=9/30 и 20/30

4/5 и 4/9= 36/45 и 20/45

1/2 и 1/7 =7/14 и 2/14

5/8 и 7/11 =55/88 и 56/88

4/25 и 9/10=8/50 и 45/58

5/6 и 4/9 =15/18 и 8/18

3/20 и 2/15 =9/60 и 8/60

3/4 и 9/10 =15/20 и 18/20

3/9 и 15/25 =75/225 и 135/225

4/6 и 6/8 =16/24 и 18/24

2/4 и 6/9 =18/36 и 24/36

21/98 и 20/84=126/588 и 140/588