GCSE Maths Question that caused outrage after being called ridiculously hard

The question on 05/06/15 GCSE maths paper was as follow:

"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." 

Q. Show that n²-n-90=0

10 Marks

It took me, only 4 mins to solve this. Average should take 10 mins for 10 marks.

I am a degree student!!!! Enjoy

Ans: n=10 more solutions to follow if I don't upload in a week, tell me in the comment below.
Clue start with 6/n-((6-5)/(n-1))=1/3 the sum gets much simpler.