Behave, thats very simple maths, definately GCSE level or below, nothing like you would come across in an 'A' level let along a degree!

If you are in the top sets for maths, you would be doing that sot of thing at 13/14 typically back in my day (for normal people I mean as opposed to nerds like me who took their maths gcse at 14 anyway)

As per the workings I showed above, you simply add up the number of computers, then add up the number of reboots, and the average number of reboots per machine is simply one divided by the other.