@WillBurnz777@AGoldmund It's pe(md)(as) actually as multiplication and division are done left to right, same thing with addition subtraction. So 64 is correct.
@NoContextHumans Depends how well she served them. If it was poor or mediocre this tip is fair. At least she got a tip. Had it been 0 I'd hear you out. And this comes from someone who delivered pizza for 8 years.