41又3分之1乘4分之3+51又4分之1乘5分之4
=（41+1/3）3/4+（51+1/4）4/5
=41x3/4+1/3x3/4+51x4/5+1/4x4/5
=123/4+1/4+204+1/5
=124/4+205/5
=31+41
=72