41又1/3x3/4+51又1/4x4/5+61又1/5x5/6=（40+4/3）x3/4+（50+5/4）x4/5+（60+6/5）x5/6=40x3/4+4/3x3/4+50x4/5+5/4x4/5+60x5/6+6/5x5/6=30+1+40+1+50+1=123
写得真是乱七八糟……
124/3x3/4+205/4x4/5+306/5x5/6=31+41+51=123
