The depreciation is (15,000 – 1,000) / 5 = $2,800 per year.
In the year of sale they only have the asset for 3 months (1 July to 30 September) and so the charge is 3/12 x 2,800 = $700.
Have you not watched the free lectures working through all of the examples? There is no point in using the notes without watching the lectures because they are only lecture notes. It is in the lectures that I explain and expand on the notes.