0.25*5分之4+2.5%
=1/5-1/40
=7/40
2.3*1.5+4.5\0.75
=3.45+6
=9.45
6分之5*0.25+4分之1*6分之1
=（5/6+1/6）*1/4
=1*1/4
=1/4