(HELP)(3DS ROM) How do you extract .arc files (monster hunter 4 ultimate)

[Waddle dissel]

First post here yay

Finally i extracted the files from a decrpyted rom file of MH4U online

But the thing is that i dont know how to open .arc files

Is there a way to do this? if so how?

Also i dont have a 3ds, I used a rom i found online

Sorry if i sound dumb, im semi new to all of this

Thanks!