Answer
Please see the work below.
Work Step by Step
$KF_{(s)} → K^{+}_{(g)} + F^{-}_{(g)}$
$ \Delta H^{\circ}_{lattice} = U$ is the lattice enthalpy during the breaking of ionic compound KF into its constituent ions in a gaseous state.
When these gaseous ions are added to water it forms aqueous ions. The enthalpy change during this process is hydration enthalpy.
$K^{+}_{(g)} + H_{2}O_{(l)} → K^{+}_{(aqu)}$
$ \Delta H_{hydr(K^{+})} $, is the hydration enthalpy of potassium ion.
F^{-}_{(g)} + H_{2}O_{(l)} → F^{-}_{(aqu)}
$ \Delta H_{hydr(F^{-})} $, is the hydration enthalpy of fluoride ion.
The heat of solution of KF is the sum of lattice enthalpy and hydration enthalpies of two ions.
$ \Delta H_{solution} = U + \Delta H_{hydr(K^{+})} +\Delta H_{hydr(F^{-})}$
