Average surroundings

Can you work out Ali's age based on the diagram?
Age
14 to 16
Challenge level
filled star filled star empty star
Exploring and noticing Working systematically Conjecturing and generalising Visualising and representing Reasoning, convincing and proving
Being curious Being resourceful Being resilient Being collaborative

Problem

Average Surroundings


Ali (A) and Baba (B) are shown surrounded by six thieves. The thieves' ages are given. Ali's age is the average of his four nearest neighbours', and so is Baba's. How old is Ali?

 

If you liked this problem, here is an NRICH task which challenges you to use similar mathematical ideas.