5/11 - 3/11 + 7/11 = 9/11
9 13/19 + 818/19−315/198 18/19 - 3 15/19818/19−315/19 = 9 + 8 - 3 + 13/19 - 15/19 = 14/19
10 4/21 - 410/21+319/214 10/21 + 3 19/21410/21+319/21 = 10 - 4 - 3 + 4/21 - 10/21 - 19/21 = 3/21 = 1/7
5/11 - 3/11 + 7/11 = 9/11
9 13/19 + 818/19−315/198 18/19 - 3 15/19818/19−315/19 = 9 + 8 - 3 + 13/19 - 15/19 = 14/19
10 4/21 - 410/21+319/214 10/21 + 3 19/21410/21+319/21 = 10 - 4 - 3 + 4/21 - 10/21 - 19/21 = 3/21 = 1/7