Chem problem

An electric furnace produces phosphorus by the following reaction:
Ca3(PO4)2(s) + C(s)+SiO2(s)= CaSiO3(s)+CO(g)+P(I)

An initial reaction mixture contains 1500g calcium phosphate, 250 g carbon and 1000g silicon dioxide.
a) What is the limiting reactant?
b) What is the theoretical yield of phosphorus?
c) After the reaction of the slag (solid residue) was analyzed. It contained 3.8 % Carbon, 5.8 % Phosprorus, and 26.6 % Calcium by mass. What was the actual yield of phosphorus? What was the percent yield?