Question 9
An and Bình both travel from $S$ to $F$. An follows $S\to A_1\to A_2\to A_3\to A_4\to A_5\to A_6\to A_7\to A_8\to A_9\to F$, while Bình follows $S\to B_1\to B_2\to F$. Their total distances are equal. Find $A_2A_3+A_4A_5+A_6A_7$, in metres.
