奥赛题:3.7×15+21×4.5怎么做

3.7×15+21×4.5
=(4.5-0.8)×15+21×4.5
=4.5×15+21×4.5-0.8×15
=4.5×(15+21)-0.8×15
=15×0.3×36-0.8×15
=15×(4×9×0.3-4×0.2)
=15×[4×(2.7-0.2)]
=15×4×2.5
=15×10
=150

3.7*15+21*4.5
=3.7*15+2.1*45
=3.7*15+2.1*3*15
=3.7*15+6.3*15
=（3.7+6.3）*15
=10*15
=150

3.7*3*5+3*7*4.5
=3*（3.7*5+4.5*7）
=3*（18.5+31.5）
=120
呵呵，好像还是不太简便。。

55.5+94.5=150