Пошаговое объяснение:

1)

7/9 и 21/27 => 7/9 и (21:3)/(27:3) => 7/9 и 7/9

7/9 = 21/27

2)

5/28 и 25/140 => 5/28 и (25:5)/(140:5) => 5/28 и 5/28

5/28 = 25/140

3)

1/5 и 13/65 => 1/5 и (13:13)/(65:13) =>1/5 и 1/5

1/5 = 13/65

4)

9/11 и 36/44 => 9/11 и (36:4)/(44:4) => 9/11 и 9/11

9/11 = 36/44