If you have left university for some time, chances are you did not do any math in that time inbetween, if you are a software engineer. Software engineering requires logical thinking in a different way than mathematics, so we do not really keep our mathematics skills up to date.
Looking at document, I can remember touching the necessary mathematics to solve this, but not having done any mathematics of the kind makes me too rusty in mathematics to be able to solve it.
With a bit of revision, someone having seen this somewhere in undergrad will probably be able to solve it.