We subtract the enthalpies of the reactants from that of the products:
[tex]2\Delta
H(NaCl)+\Delta H(Cs_2 SO_4)-2\Delta H(CsCl)-\Delta H(Na_2 SO_4) \\
=2(-411)+(-1400) -2(-415)-(-1380) \\ = -12 kJ[/tex]
Since this is < 0, this is an exothermic reaction.