1-7/18 4-2/9 15 2/7-7 11-5 3/13 6 3/5-3 5/12 9 2/5-3 7/8 19 7/12+43 5/12 7 7/15+4 11/12 5 5/9+7 3/5+1 7/18 8 7/8+3 2/5-2

1 - 7/18 = 18/18 - 7/18 =11/18;

4 - 2/9 = 36/9 - 2/9 = 34/9 = 3 7/9;

15 2/7 - 7 = 107/7 - 49/7 = 58/7 = 8 2/7;

11 - 5 3/13 = 143/13 - 68/13 = 75/13 = 5 10/13;

6 3/5 - 3 5/12 = 33/5 - 41/12 = 396/60 - 205/60 = 191/60 = 3 11/60; 

9 2/5 - 3 7/8 = 47/5 - 31/8 = 376/40 - 155/40 = 221/40 = 5 21/40; 

19 7/12 + 43 5/12 = 235/12 + 521/12 = 756/12 = 63;

7 7/15 + 4 11/12 = 112/15 + 59/12 = 448/60 + 295/60 = 743/60 = 12 23/60;

5 5/9 + 7 3/5 + 1 7/18 = 50/9 + 38/5 + 25/18 = 500/90 + 684/90 + 125/90 = 1309/90 =

= 14 49/90; 

8 7/8 + 3 2/5 - 2 3/4 = 71/8 + 17/5 - 11/4 = 355/40 + 136/40 - 110/40 = 381/40 = 9 21/40.