求简便算法(75+240)*(20-5)== =脱式计算

问题描述:

求简便算法
(75+240)*(20-5)
=
=
=
脱式计算

(75+240)*(20-5)
=(15+300)*15
=15*15+300*15
=4725

(75-5)*(20+240)
=70*260
=1820