48又7/8+57.125x1/2-1/2=(48x8+7)/8+56.125=48+0.875+56.125=48+57=105
48又7/8+57.125×1/2-1/2=48又7/8+(57又1/8-1)×1/2=48又7/8+56又1/8×1/2=48又14/16+28又1/16=76又15/16