Do You Add The Whole Sell Amount or % Amount to The BAS When Getting Rid of Business Assets with Some Private Usage?

Sorry was going to call the ATO on Monday to ask this question but I will be back to my full days work so I wont be able to call and wait more than 30min to 60mins

Say I bought something for $5000 initially with 30% business usage only, and claimed the GST credit at the time for the 30%. Now I sold this item for $3000, with my 30% business usage the GST which is payable to the ATO should be $3000 x 30% = $900/11 = $81.81 <———- This part I understand.

However what I am not sure about is when adding this Asset Sale to the Total Sales on the BAS, do I add the entire $3000 to the Total Sales or do I only add $900 to the Total Sales on the BAS (Which is the 30% business usage)?

My understanding is I should only add $900 to the Total Sales of the Business as the rest is private usage. Am I right or wrong I wonder?

Thanks many.