Почитай какое число должно быть в рамки там 20

1.

7/12 + 1/6 = 7/12 + 2/12 = 9/12 = 3/4 = 0,75

1 1/3 * 3/10 = 4/3 * 3/10 = 4/10 = 0,4

4/10 : 4/5 = 4/10 * 5/4 = 1/2 = 0,5

0,75 - 0,5 = 0,25

2.

2/15 * 5/6 = 1/9

1/12 * 1 1/4 = 1/12 * 5/4 = 5/48

5/48 + 1/16 = 5/48 + 3/48 = 8/48 = 1/6

1/6 - 1/9 = 3/18 - 2/18 = 1/18

3.

2 1/2 - 2 = 1/2

1/2 * 3 = 3/2 = 1 1/2 = 1,5

1,5 + 0,5 = 2

2 : 6 = 1/3

4.

1 3/8 - 1/4 = 1 3/8 - 2/8 = 9/8 = 1 1/8

1 1/8 + 5/12 = 1 3/24 + 10/24 = 1 13/24

1 13/24 * 2 = 37/24 * 2 = 37/12 = 3 1/12

3 1/12 : 37 = 37/12 * 1/37 = 1/12

5.

1/2 * 2/3 = 1/3

1/3 + 5/8 = 8/24 + 15/24 = 23/24

5/12 + 13/24 = 10/24 + 13/24 = 23/24

23/24 : 23/24 = 1