Learn Portuguese (Portugal): O carro velho custa quinhentos euros.

In Portuguese, adjectives (words that describe things) usually come after the noun they are describing. So instead of "old car", you say carro velho (car old).

I know that "five" is cinco. Why is "five hundred" quinhentos instead of "cinco centos"?

While many hundreds in Portuguese are made by adding -centos to the number (like quatrocentos for 400), 500 is a special exception. It changes completely to quinhentos, which you just have to memorize.

How do I pronounce the "lh" in velho?

The lh sound in Portuguese is similar to the "lli" sound in the English word "million". You make it by pressing the middle of your tongue to the roof of your mouth.

Why does the verb custa end in an "a"?

Custa is the "it" form of the regular verb custar (to cost). Because o carro (the car) is a single object, we use the same verb ending as we would for "he" or "she".