Duration of Stay in China ( HK, China, Taiwan)

Dear All,

If I was to visit Hong Kong for 5 days, would I still be able to travel around China for 15 days, if i was to hold a Singapore passport?

Additionally, is it possible to stay in China for 15 days, then to Taiwan for 2 days, and back to China again for another 15 days of stay?

Thanks again and looking forward to your reply