Three calorimetry experiments are performed, with the choice of chemical systems such that the enthalpy changes of two of the reactions should equal the enthalpy change of the third. The three thermochemical reactions are:

1. HBr(aq) + KOH(aq) → H2O(l) + KBr(aq) DH1 = ? kJ

2. KOH(s) → KOH(aq) DH2 = ? kJ

3. KOH(s) + HBr(aq) → H2O(l) + KBr (aq) DH3 = ? kJ

a) Use Hess's law to show how two of these equations can be added to yield the third equation.

i know that #1 and #2 when you add them together you get #3

b) now here's the harder question using this table calculate the enthalpy change in each system.

as seen on the chart attached

how do i find the enthalpy of each reaction >.<