YOU SAID:

I don't understand why this is so easy.

INTO JAPANESE

これがなぜこんなに簡単なのかわかりません。

BACK INTO ENGLISH

I do not know why this is so easy.

INTO JAPANESE

私はなぜこれがそんなに簡単なのかわかりません。

BACK INTO ENGLISH

I do not know why this is so easy.