This problem was solved by Ali Abu-Hijleh (aged 13) and Prateek Mehrotra (aged 14), both from Riccarton High School in Christchurch, New Zealand, by Malcolm Findlay and Hamish Hepburn, both from Madras College in St Andrews, Scotland, and by Daniella Yule, Alice Unwin and Alice Lewin from The Mount School in York.

Well done to you all.

Below are a couple of the solutions we received.

By Daniella Yule, Alice Lewin and Alice Unwin

By Prateek Mehrotra