Learn Farsi: خریدن ماشین جدید مشکل نیست.

In Farsi, the infinitive form (which always ends in -dan or -tan) can be used exactly like the English "-ing" noun form. So kharidan can mean "to buy" or "buying" depending on how it is used in the sentence.

How do I extract the present stem from kharidan?

To find the past stem, you simply drop the -an to get kharid. However, present stems in Farsi are often irregular and must be memorized. The present stem for kharidan is khar.

Is there an invisible connecting sound between kharidan and mâshin?

Yes! Because kharidan is acting as a noun here, it connects to the next noun using the ezafe sound. You pronounce it kharidan-e mâshin, which literally translates to "the buying of a car".

Why is the word for "new" placed after "car"?

In Farsi, adjectives almost always come after the noun they describe. They are also linked by the invisible ezafe sound, so "new car" becomes mâshin-e jadid.

Doesn't moshkel usually mean "difficult"?

Yes, moshkel is often used as an adjective meaning "difficult" or "hard". But it is also a very common noun meaning "problem". In this sentence, translating it as "a problem" or "difficult" both work perfectly.