百分率的應用

20x65%
=20x65/100
=13

600 - 600x25%
=600 - 150
=450ml

2010-10-05 22:49:46 補充：
OR Q2
600x(1-25%)
=600x75%
=600x75/100
=450ml

2010-10-06 12:25:37 補充：
formula:
餘下數= 原本數量X(1-用去百分比)

20的65%是:
20x65%

=20x65/100%

=13