You were almost right. It is technically 72.
However, 216 is a multiple of 72.
You pretty much figured it out when you wrote: [tex]\frac{216}{72} = 3[/tex]
[tex]\frac{360}{5} = 72[/tex]
Multiples of 72: [tex]72, 144, 216[/tex]
That's what I understood. I hope this helps at least a little. :)
