A difficult maths question about a girl called Hannah's sweets left thousands of Kent teenagers stumped yesterday.

The tricky equation about the probability of taking two orange sweets from a bag appeared in an Edexcel GCSE exam paper sat by pupils across the country.

Within hours, youngsters had taken to Twitter to vent their frustration - and the hashtag #Edexcelmaths was trending.

A petition has since been launched on Change.Org calling on the exam board to lower the grade boundaries or allow candidates to re-take the exam.

A student writing on the website said: "All past papers were similar in a way and they are the resources that were that were used by students all through the country to help them with this paper... a lot of people have done badly and would appreciate a retake of a new test or lower grade boundaries."

Edexcel's owners Pearson say pupils will be "treated fairly" when the papers are marked.

Here is the question:

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

Hannah takes a sweet from the bag. She eats the sweet. Hannah then takes at random another sweet from the bag. She eats the sweet.

The probability that Hannah eats two orange sweets is 1/3. Show that n²-n-90=0

A spokesman said: "Our exam papers are designed by an experienced team of expert teachers with a deep understanding of the subject matter.

"They make sure our papers are set at the appropriate level to test the full range of students' abilities."

Here's how students reacted to the "impossible" paper on Twitter:

Did you sit the exam? What did you think? Email news@thekmgroup.co.uk or comment below.