3/9 и 15/25
3/9 = 1*3/3*3 = 1/3
15/25 = 3*5/5*5 = 3/5
1/3 = 1*5/3*5 =5/15 и 3/5 = 3*3/5*3 = 9/15
4/6 и 6/8
4/6 = 2*2/3*2 = 2/3
6/8 = 2*3/2*4 = 3/4
2/3 = 2*4/3*4 = 8/12 и 3/4 = 3*3/4*3 = 9/12
2/4 и 6/9
2/4 = 1*2/2*2 = 1/2
6/9 = 2*3/3*3 = 2/3
1/2 = 1*3/2*3 = 3/6 и 2/3 = 2*2/3*2 = 4/6
21/98 и 20/84
21/98 = 3*7/14*7 = 3/14
20/84 = 4*5/4*21 = 5/21
3/14 = 3*21/14*21 = 63/294 и 5*14/21*14 = 70/294
