Algebra: X + Y = What?

Here's a thing from the New York Times. One thing I always think about headlines and titles is that they should very, very rarely be questions. If your reader can answer the question quickly, easily and definitively, the reader will not be a reader for you. That's fine if you just need page views. But if you want to actually persuade people with your persuasive essay, I would ding any editor who changes your headline to a question.