http://a367.yahoofs.com/hkblog/rDkOb8SWERnmmaR4UeTpiIbmgvVT_2/blog/20110504090925275.jpg?ib_____DG7zoG3Fh
上圖是利用比求未知數,其實4/5=X/50是方程,可否兩邊同時乘5?
http://a367.yahoofs.com/hkblog/rDkOb8SWERnmmaR4UeTpiIbmgvVT_2/blog/20110504091748136.jpg?ib_____DQ1HzfBBx
為何上圖要乘100,乘10不也行嗎??