How to solve the maths GCSE question about Hannah's sweets that went viral

Students flooded social media this week to ridicule this tricky maths teaser about a teenage girl and her struggle with a sugary diet. Here's how to solve it.

Earlier this week this question was in the Edexcel Maths GCSE paper:

There are n sweets in a bag. 6 of the sweets are orange. The rest of the sweets are yellow.

Hannah takes a random sweet from the bag. She eats the sweet.