=2 4/7- 1 3/7 +3 1/7 -2 5/7 = 1 1/7 +3 1/7 - 2 5/7 = 4 2/7 - 2 5/7 = 30/7 - 19/7 = 11/7 = 1 4/7
2 4/7-1 3/7+3 1/7-2 5/7=1 4/7 1)2 4/7-1 3/7=1 1/7 2)1 1/7+3 1/7=4 2/7 3)4 2/7-2 5/7=3 9/7-2 5/7=1 4/7