27/5-【(-2+17/5)-(45/15-18/5)】

问题描述:

27/5-【(-2+17/5)-(45/15-18/5)】

27/5-【(-2+17/5)-(45/15-18/5)】
=27/5-(-2+17/5-27/5)
=27/5+27/5-17/5+2
=37/5+2
=7又2/5+2
=9又2/5