风马牛不相及的英文：
[Literal Meaning]
wind/horse/ox/not/mutually/related
to be totally unrelated like wind, horse and ox

[解释]
事物彼此毫不相干。

[Explanation]
to have absolutely nothing in common with each other

[例子]
他在文章中举的例子根本就风马牛不相及，没有说服力。

[Example]
The examples he provided in his article were actually totally unrelated and not convincing at all.

[英语等价词]
horse of a different color

Have nothing in common with; totally unconnected; two different unrelated things
风马牛不相及

A question about arithmetic is irrelevant in a music lesson.
在音乐课上，一个数学的问题是风马牛不相及的。

For "what the Mediterranean Sea is for Italy the eastern shore of the baltic is for Germany"
两者风马牛不相及，就好像"地中海属于意大利而波罗的海东岸属于德国"。