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
（10-2.8）*14.5+17*2.8=145-2.8*14.5+2.8*17=145+2.5*2.8=145+2.5*0.4*7=145+7=152
原式
=7.2*14+7.2*0.5+17*2.8
=72*1.4+3.6+34*1.4
=106*1.4+3.6
=140+8.4+3.6
=140+12
=152
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+2.5×4×0.7
=145+10×0.7
=145+7
=152
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