Сократите дроби и их к общему знаменателю 3/9и15/25 ; 4/6и6/8; 2/4и6/9; 21/98и20/84

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