[56x(5/7-2/8)-0.625x0.5+5/8+1/2x62.5%]÷2又1/4=（56×5/7-56×2/8-5/8×1/2+5/8+1/2×5/8）÷9/4=[40-14-5/8]×4/9=203/8×4/9=203/18
