I don't even do geography but the formula is
vertical scale/horizontal scale
You just need to look at the graphs and what each axis represents.
For example, the 2003 hsc paper included a question on vertical exaggeration.
http://www.boardofstudies.nsw.edu.au/hsc_exams/hsc2003exams/pdf_doc/geography_03.pdf
16 a)Calculate the vertical exaggeration of the cross-section shown.
You can see that on the vertical hand side of the graph provided that each one centimetre represents 10 m
All you need to do then is find what each centimetre of the horizontal represents (would be a lot easier to calculate if I could find the stimulus booklet of the cross section for 2003)
anyways,
it would just be (1/10)/(1/what each cm reps)
which is (1/10)/(1/500) in this case
so the VE = 50
Vertical exaggeration is expressed through a number only, not through metres or cm, because it's measure the relative degree of scale of the map.