1) 3/7+14/19+4/7+5/19
2)7/16+11/42+9/16+17/42
3)5/18+11/81+7/18+5/81

1)2

2)1 2/3

3)70/81

вот правильные ответы

1) 3/7 + 4/7 + 14/19 + 5/19 = 7/7 + 19/19 = 1 + 1 = 2

2) 7/16 + 9/16 + 11/42 + 17/42 = 16/16 + 28/42 = 1 + 2/3 = 1 2/3

3) 5/18 + 7/18 + 11/81 + 5/81 = 12/18 + 16/81 = 2/3 + 16/81 = 54/81 + 16/81 = 70/81