问一道og里的数学题哈

问一道og里的数学题哈： If candy bars that regularly sell for 0.4 each are on sale at two for 0.75,, what is the percent reduction in the price of two such candy bars pruchased at the sale price?

答案是六又四分之一percent我选的是六又三分之二， 我看了一下解释答案把sale price认为是0.8，可是我认为sale price 应该是0.75，麻烦牛牛指点一下

（0.75-0.4*2）/0.8=-6.25%

答案是问price减少了多少百分比

分母就是初始的状态