Can anyone help me with this formula?

[1] P4 + [3] O2=[2] P2O3

Explanation:

you can first solve for amount of O2 in the equation because reactant had O2 and product had O3, so the amount of O2 should be 3 and amount of O3 should be 2, which gets u to 6 moles of oxygen for both reactant and product.  then you can balance the P4, and 1 mols of P4 = 2 moles of P2, which matches with the amount of mols for O3 as well. therefore you can get P4 + 3O2 = 2P2O3