用简便方法计算(-421)x(-1/4)-0.25x(-7又1/2)-28.5x25%
问题描述：
用简便方法计算(-421)x(-1/4)-0.25x(-7又1/2)-28.5x25%
答
=421*1/4+1/4*15/2-28.5*1/4
=1/4*(421+7.5-28.5)
=1/4*(421-21)
=1/4*400
=100