I am very confused by this article title in New Yorker:
Shouldn't it be "How much does"? Why do?
The answer is
How much do Pacquiao-Mayweather tickets cost? (Better off without capitalization when you're asking a question from your friend)
The misunderstanding, I believe, is caused by these two guys: Pacquaio and Mayweather.
If you run into this kind of problem, I suggest
Isn't the sentence like this?
How much does/do ____ cost?
We need to fill that blank with either something or somethings. To find out which, do the next step.
What are the words in this phrase? Pacquiao-Mayweather and tickets. We eliminate both. The one that makes sense, has the head of the phrase.
How much do * Pacquiao-Mayweather cost?
How much do tickets cost?
You see, the price is about the tickets. So, tickets is the head of the noun phrase.1
Verbs, generally, follow (or agree with) the nouns they're pertaining to. In this step, after we have identified the head of the noun phrase, we have to write a verb that agrees with it.
Tickets is a plural noun. So, the verb needs to be plural.
How much do/
Done like a charm! 2 :)
1: If you want a more comprehensive way of determining the head of noun phrases, visit here.
2: If things are still vague, you can leave me a comment.