2/3×1/12+1/4×1/12=（2/3+1/4）×1/12=（8/12+3/12）×1/12=11/12×1/12=11/144
2/3*1/12+1/4*1/12=(2/3+1/4)*(1/12)=(8/12+3/12)*(1/12)=(11/12)*(1/12)=11/144
11/144
