X + 1\3 = 1\2
X = 1\2 - 1\3 = 3\6 - 2\6 = 1\6
....................................................
X + 1\3 = 1 1\6 = 7\6
X = 7\6 - 1\3 = 7\6 - 2\6 = 5\6
....................................................
X + 1\3 = 1 1\9 = 10\9
X = 10\9 - 1\3 = 10\9 - 3\9 = 7\9