The energy released in the reaction is a difference of binding energies of daughter and parent nuclei.

Binding energy of ​He = $4 \times 7 MeV = 28 MeV$

Binding energy of deutron = $2 \times 1.1 MeV = 2.2 MeV$

Hence, energy released = binding energy of ​He−2×binding energy of deutron = 28−(2×2.2)=23.6MeV