вычислите 6 2/7-4 1/7; 12 1/9-5 4/9; 8 4/5-3 1/5; 18 2/11-7 5/11.

6 2/7-4 1/7=2 1/7 12 1/9-5 4/9=9 19/9-5 4/9=5 15/9=6 6/9=15 2/3 8 4/5-3 1/5=5 3/518 2/11-7 5/11=16 24/11-7 5/11=11 19/11=12 8/11