Count rows if they meet conditions in two columns

[williaml]

Hi, can you make your dataset reproducible?

FAQ: How to do a minimal reproducible example ( reprex ) for beginners

Please feel free to improve this FAQ, just keep in mind the general goal of making it friendly for r beginners (and if possible for non native English speakers as well) EDIT: Translations to other languages are also welcome (please try to keep translation as close as posible to the original English text)