Chemistry quick help please?

No. of moles of HCl = (0.100 mol L⁻¹) × (100/1000 L) = 0.01 mol
HCl completely dissociates in aqueous solution to give hydronium ions.
No. of moles of H₃O⁺ ions = 0.01 mol

No. of moles of NaOH = (0.100 mol L⁻¹) × (200/1000 L) = 0.02 mol
NaOH completely dissociates in aqueous solution to give hydroxide ions.
No. of moles of OH⁻ ions = 0.02 mol

Equation for the reaction :
H₃O⁺(aq) + OH⁻(aq) → 2H₂O(l)
Mole ratio H₃O⁺ : OH⁻ = 1 : 1

Initial no. of moles of H₃O⁺ ions = 0.01 mol
Initial no. of moles of OH⁻ ions = 0.02 mol > 0.01 mol
Hence, OH⁻ is in excess, and H₃O⁺ completely reacts.

No. of moles of H₃O⁺ reacted = 0.01 mol
No. of moles of OH⁻ reacted = (0.01 mol) × 1 = 0.01 mol
No. of moles of OH⁻ left in the final solution = (0.02 - 0.01) mol = 0.01 mol
Volume of the resulting solution = (100 + 200) mL = 300 mL = 0.3 L

[OH⁻] in the resulting solution = (0.01 mol) / (0.3 L) = 0.0333 M
pOH = -log(0.0333) = 1.5
pH = pKw - pOH = 14 - 1.5 = 12.5