7.5*[63.9/(7-2.5)简便计算
问题描述：
7.5*[63.9/(7-2.5)简便计算
答
7.5*[63.9/(7-2.5)]
=7.5/5*63.9/0.9
=1.5*71
=106.5
答
7.5*[(63+0.9)/4.5]
=7.5*[(7*9+0.1*9)/0.5*9]
=15*(7+0.1)
=105+1.5
=106.5
答
原式=7.5*63.9/4.5
=7.5/5*63.9/0.9
=1.5*71
=106.5