2-【0.25/8分之1-(5分之3-10%/6分之1)/5分之9】/1又3分之1
=2-【2-(5分之3-5分之3)/5分之9】/1又3分之1
=2-【2-0/5分之9】/1又3分之1
=2-2/1又3分之1
=2-1.5
=0.5