"How ya goin" is a common Australian expression used to ask someone how they are doing. This colloquial phrase has a few different synonyms that can be used in place of it. Some alternatives include "how's it going," "how are you," "how's things," "how's life treating you," and "what's up." These phrases are all similar in nature and are intended to inquire about someone's well-being. Depending on the context and the level of familiarity with the person you are speaking with, you can use any of these expressions to greet them and initiate a conversation.