Listing all reactants and products, photosynthesis can be described as:
6 CO2 + 12 H2O → C6H12O6 + 6 O2 + 6 H2O
But because water is both a reactant and a product, the equation can be simplified accounting for net water consumption, which is:
6 CO2 + 6 H2O → C6H12O6 + 6 O2
Carbon dioxide + Water + Light energy → Glucose + Oxygen