How to determine which one undergoes oxidation and which one undergoes reduction? For this equation.
Use a simple rule
Oxidation is gain of oxygen
Reduction is gain of hydrogen or loss of oxygen
In this Equation you can see
2Ca3(Po4)2 after reaction changes into P4 on right hand side which means it has undergone reduction .
10Co and Casio3 have undergone Oxidation because oxygen is added to their molecules. Hope this helps thanks