casey is accountant who operates her business from a property in the city of adelaide. He pays $$200$ per week which is less than market value rent.

Casey is planning to re$-$locate her practice to the outer suburbs of Adelaide & so will be putting the current business premises on the market. The real estate has valued the property at $$860,000.$

With reference to legal authority, advise casey of the GST implications of selling her property, explaining how GST if any, would be calculated.