（9又1/2+7又1/6+5又1/12+3又1/20+1又1/30）*12=

（9又1/2+7又1/6+5又1/12+3又1/20+1又1/30）*12=
（9又1/2+7又1/6+5又1/12+3又1/20+1又1/30）*12=

（9又1/2+7又1/6+5又1/12+3又1/20+1又1/30）*12=
（9又1/2+7又1/6+5又1/12+3又1/20+1又1/30）*12
=（9+7+5+3+1+1/2+1/6+1/12+1/20+1/30）x12
=(25+1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6)x12
=(25+1/2-1/6)x12
=25x12+1/2x12-1/6x12
=25x4x3+6-2
=300+4
=304

（9又1/2+7又1/6+5又1/12+3又1/20+1又1/30）*12
=(9+7+5+3+1)*12+(1/2+1/6+1/12+1/20+1/30)*12
=25*12+(1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6)*12
=300+(1-1/6)*12
=300+10
=310

先分开乘进去变成 19*6+43*2+61+183/5+62/5 中间省去了约分和 变成假分数 然后这样就简单多了该和的就和 最后答案310