2 1/6 − (−8/3) + (−4 7/9)
2 1/6 = 13/6, -8/3 = -16/6, -4 7/9 = -43/9
13/6 = 39/18, -16/6 = -48/18, -43/9 = -86/18
39/18-(-48/18)+(-86/18) = 39/18 + 48/18 - 86/18 = 87/18 - 86/18 = 1/18
