Note added to
>>27:
When A and B are numerical quantity, "A per B" can be, in most case, the said three types of translation. But this is an exception:
50 miles per hour (50mph) -> 時速５０マイル
Also, if B refers to an action as in "per drive" and "per move", it is often translated as 度に (tabi-ni). For exapmle,
It costs 5 dollars per use. -> 使う度に５ドルかかる
Also,
>>26 said "it's just ~" is たったの〜. But I feel the exact meaning of the English phrase falls into somewhere between "たったの〜," "ほんの〜," and "まあ〜," and I think "まあ〜" is the closest. For instance, if you want to say, "It's just a matter of preference," then it should be まあ好みの問題です。It sounds funny if you say たったの好みの問題です。or ほんの好みの問題です。