56+27+16
=5/6+1/6+2/7
=1+2/7
=9/7
89-16+23
=16/18-3/18+12/18
=25/18
16+58+28+56
=1/6+5/6+(5/8+2/8)
=1+7/8
=15/8
23-(14+18)
2/3+(2/8+1/8)
=2/3+3/8
=16/24+9/24
=25/24
178-（78+14)
=17/8-7/8-1/4
=5/4-1/4
=1
34-27+14-57
=3/4+1/4-(2/7+5/7)
=1-1
=0
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