One of the most common ways of forming a question in Chinese is to add 嗎 at the end of a statement. Hence 你好! (Hi!) becomes 你好嗎? (How are you?)
This is to be used to redirect the question originally addressed to you. Its meaning is equivalent to "and you?" "what about you?" or "how about you?"
A: 你好嗎?
How are you?
B: 我很好, 你呢?
I am fine, and you?
A: 你忙嗎?
Are you busy?
B: 我不忙, 你呢?
I am not busy, what about you?