15/16+（7/16-1/4)÷(1/2) =15/16+(7/16-1/4)×1/(1/2) =15/16+(7/16-1/4)×2 =15/16+2×7/16-2×1/4 =15/16+7/8-1/2 =15/16+14/16-8/16 =(15+14-8)/16 =21/16
