(-1/24)/(1/6-1/8+1/12)
=-1/(1/6×24-1/8×24+1/12×24)
=-1/（4-3+2）
=-1/3-1是哪里来的(-1/24)/(1/6-1/8+1/12)=（-1/24×24）/(1/6×24-1/8×24+1/12×24)=-1/（4-3+2）=-1/3