A couple things to consider:
1) Since this compound contains both metals and nonmetals, it is an ionic compound. So, not all of the components of the compound will be covalently bonded together. What are the ions that form this compound?
2) Phosphorus is in the 3rd period, meaning that it can expand its valence shell to accommodate more than 8 electrons (i.e. it is an exception to the octet rule).