3分之2+8分之1除75%
=2/3+(1/8)/(3/4)
=2/3+1/6
=5/6;
10除9分之4+125%
=45/2+5/4
=95/4;
8分之3除（1-2分之1-25%）
=(3/8)/(1-0.75)
=(3/8)/(1/4)
=3/2