Here is the place to go to be...

Here is the place to go to be sure:
https://www.ato.gov.au/individuals-and-families/investments-and-assets/capital-gains-tax

My calc on your example is:
ST GC 15k
apply CLoss of 15k
for zero net ST (residual CLoss 85k)
then
LT CG 250k
minus Closs -85k
net LT CG is 165k
halved LTCG becomes 82.5k (to be taxable)

Check it - if I am wrong please reply here - if I am correct, please send money!
PS NOT FINANCIAL ADVICE (just to be very clear in case a pedantic litigious lawyer who does not understand humour reads the previous line)