51又三分之二÷三分之五+71又四分之三÷四分之七+91又五分之四÷五分之九
=155/3*3/5+287/4*4/7+459/5*5/9
=31+41+51
=123
3又四分之三×1.25+37.5×0.975－375%
=15/4*125/100+375/10*975/1000-375/100
=5/4*375/100+375/100*975/100-375/100
=375/100*(5/4+975/100-1)
=375/100*(125/100+975/100-100/100)
=375/100*10
=37.5