Percentages - Selling Problems 百分數 - 買賣問題

Apply percentage changes to solve simple selling problems.
運用百分數變化解答簡單的買賣問題。

Eng. ver.: http://www.geogebratube.org/material/show/id/64151 (Download GeoGebra file)
中文版:http://www.geogebratube.org/material/show/id/64158 
(Download GeoGebra file)