#### How much balast and cement for footings?

How much ballast and cement do I need for cubed of footings? I have cubed of footings to concrete. How many tonne bags of ballast and 25kgs bags of cement will I need? How do I work out how much sand and cement I will need for rendering 100 square metres. It is 100 square Metres roughly. Building a 2 high edge and need advice