Hardest maths questions: simultaneous diophantine equations 

This question from the 2007 Australian Mathematics Competition (senior division) involves 3 simultaneous equations with positive integer solutions. We have to find the smallest value that x can take. 0% of students got this one right! I'll be making heavy use of the elimination method in this video, although you could use substitution instead.
You can buy past AMC exam booklets at shop.amt.edu.a...