7.2*14.5+17*2.8
=(10-2.8)*14.5-17*2.8
=10*14.5-2.8*14.5+17*2.8
=145+(17-14.5)*2.8
=145+2.5*2.8
=145+10*2.8/4
=145+7
=152
7.2*14.5+17*2.8的简便算法
7.2*14.5+17*2.8
=(10-2.8)*14.5-17*2.8
=10*14.5-2.8*14.5+17*2.8
=145+(17-14.5)*2.8
=145+2.5*2.8
=145+10*2.8/4
=145+7
=152