Concentration

A student titrates 0.100 mol/dm³ hydrochloric acid with 0.200 mol/dm³ sodium hydroxide. Which volume of sodium hydroxide is needed to completely neutralise 25.0 cm³ of the acid? (Reaction: $\text{HCl} + \text{NaOH} \rightarrow \text{NaCl} + \text{H}_2\text{O}$)