(6 5/8 - 1/2) - (5 3/4 - 2 1/6) + (9 5/8 - 7 1/3) = 4 /56
6 5/8 - 1/2 = 53/8 - 1/2 = (53-4)/8 = 49/8
5 3/4 - 2 1/6 = 23/4 - 13/6 = (69-26)/12 = 43/12
9 5/8 - 7 1/3 = 77/8 - 22/3 = (231-176)/24 = 55/24
49/8 - 43/12 + 55/24 = (147-86+55)/24 = 116/24 = 4 20/24 = 4 5/6