Пошаговое объяснение:

№1

1) 1/3 - 1/9 = 3/9 - 1/9 = 2/9

2) 18 * 2/9 = 36/9 = 4

№2

1) 2 - 3/4 - 4/5 = 1 20/20 - 15/20 - 16/20 = 40/20 - 15/20 - 16/20 = 9/20

2) 9/20 * 20 = 180/20 = 9

№3

1) 1 - 1/3 = 3/3 - 1/3 = 2/3

2) 2/3 - 1/6 = 4/6 - 1/6 = 3/6 = 1/2

3) 1/2 - 1/9 = 9/18 - 2/18 = 7/18

4) 7/18 * 18 = 7/1 * 1 = 7/1 = 7

№4

1) 5/6 + 5/9 = 15/18 + 10/18 = 25/18

2) 25/18 * 18/25 = 1/1 * 1/1 = 1