Learn Farsi: چرا شما مجبور هستید که جریمه را پرداخت کنید؟

This sentence uses the structure مجبور بودن (to be forced) followed by که (that) and the present subjunctive of the second verb. First, we conjugate the obligation: مجبور هستید (you are forced). Then, we add the subjunctive for the action: پرداخت کنید (you pay). Literally, it translates to "Why are you forced that you pay the fine?"

Why doesn't the subjunctive verb پرداخت کنید have the usual بـ (be-) prefix?

The verb پرداخت کردن (to pay) is a compound verb. With many compound verbs formed with کردن, the subjunctive بـ prefix is frequently dropped in standard Farsi. While پرداخت بکنید is grammatically possible, پرداخت کنید is much more common and natural.

What is the purpose of the word را after جریمه?

The word را is the definite direct object marker. It shows that we are talking about a specific fine ("the fine") rather than just paying fines in general. It marks جریمه as the direct receiver of the action.

Since the verb ending already tells us the subject is "you", is the pronoun شما required?

No, it is optional. Farsi is a pro-drop language, meaning the verb ending alone is enough to show who is doing the action. Including شما here just adds a bit of emphasis or clarity, similar to asking "Why are you forced to pay the fine?"