對於所有的實數定義餘數$$\text{rem}\left(x,y\right)=x-y\left\lfloor {\frac{x}{y}} \right\rfloor$$：，這裡$$\left\lfloor {\frac{x}{y}} \right\rfloor$$ 定義為小於等於$$\frac{x}{y}$$的最大整数．试求$$\text{rem}\left(\frac{3}{8},-\frac{2}{5}\right)$$之値爲何？  The remainder can be defined for all real numbers $$x$$ and $$y$$ with $$y\ne 0$$ by $$\text{rem}\left(x,y\right)=x-y\left\lfloor {\frac{x}{y}} \right\rfloor$$ where $$\left\lfloor {\frac{x}{y}} \right\rfloor$$ denotes the greatest integer less than or equal to $$\frac{x}{y}$$. What is the value of $$\text{rem}\left(\frac{3}{8},-\frac{2}{5}\right)$$?
选项为:A:$$-\frac{3}{8}$$  B:$$-\frac{1}{40}$$  C:$$0$$  D:$$\frac{3}{8}$$  E:$$\frac{31}{40}$$  请回答其中一个选项.