The enthalpies of neutralisation of a strong acid HA and weak acid HB by NaOH are −13.6 kcal/equiv and −2.9 kcal/equiv , respectively. If one equivalent of HA and one equivalent of HB are mixed with one equivalent of NaOH, the enthalpy change was found to be −6.9 kcal/equiv , calculate the distribution of NaOH to neutralise HA and HB.