If you were interviewing for a job at a company whose main revenue stream involved transporting golf balls in school buses, that might be a perfectly reasonable interview question.
If it was an engineering role I’d definitely call it a brain teaser. But for say a marketing role, an interviewers wants to see that you understand the way money flows through the business and what the parameters therein are. Maybe it’s still a brain teaser but I would say it’s relevant to the job.
The only thing changing are parameters.
EDIT: it was for the Search team, search spam prevention, can't remember role it's been 4-5 years, sorry.