Hi,
The reason you are having a hard time finding the answer is that you weren't given enough information.
The average of a set of numbers, in this case the set of numbers would be the individual agents' commissions in May, is the total of the set divided by the number of agents. The number of agents is what's missing.
Total=average*number of agents, all you were given is the average....you need the number of agents.
Hope this helps
Jim